Hearty Sausage, Mushroom & Potato Gratin: The Ultimate One-Pan Comfort Food

Imagine a dish so wonderfully versatile, it effortlessly transitions from a satisfying breakfast or brunch to a comforting dinner side. This Sausage, Mushroom & Potato Gratin is precisely that – a delicious, adaptable, and incredibly flavorful creation that will quickly become a household favorite. Whether you’re serving it alongside a perfectly roasted chicken, topping it with a fried egg for a hearty morning meal, or simply enjoying it as a stand-alone delight, you truly can’t go wrong with this rich and savory gratin.

This recipe brings together the robust flavors of Italian sausage, earthy mushrooms, and tender potatoes, all baked to golden perfection under a blanket of melted cheese. It’s the kind of meal that warms you from the inside out, offering a fantastic blend of textures and tastes. Plus, with the option to prepare much of it in advance, it’s ideal for both weeknight dinners and leisurely weekend gatherings.

Why You’ll Love This Sausage, Mushroom & Potato Gratin

One-Pan Simplicity: Many of the steps, from sautéing to baking, can be done in a single ovenproof skillet, minimizing cleanup.
Rich & Satisfying: The combination of savory sausage, hearty potatoes, and umami-rich mushrooms creates a deeply satisfying flavor profile.
Highly Adaptable: Easily customizable to fit dietary preferences or taste buds – make it spicier, vegetarian, or add extra veggies.
Make-Ahead Friendly: Prepare components or even the entire dish in advance, making it perfect for busy days or entertaining.
Versatile Serving: Excellent for breakfast, brunch, or dinner, proving its place at any table, any time.

Gathering Your Ingredients for a Perfect Gratin

The beauty of this gratin lies in its simple yet high-quality ingredients. Here’s a closer look at what you’ll need and why each component plays a vital role:

Italian Sausage: We recommend removing the casings to allow the sausage to crumble and brown beautifully, distributing its savory flavor throughout the dish. Mild Italian sausage offers a balanced taste, but if you enjoy a kick, hot Italian sausage will add a delightful spice. Consider exploring different types like sweet, fennel, or even chicken or turkey Italian sausage for a lighter alternative.
Butter: Essential for sautéing the vegetables and adding a rich, creamy depth of flavor. Salted butter is generally convenient and works well here, as precise salt control isn’t overly critical due to other savory components. If using unsalted, you might slightly increase the added kosher salt to taste.
Onions: Chopped onions provide a foundational layer of sweetness and aromatic flavor as they caramelize during sautéing. White, yellow, or sweet onions are all excellent choices, each offering a slightly different nuance to the overall taste.
Mushrooms: Sliced cremini (baby-portobello) mushrooms are a fantastic choice for this gratin. Their meaty texture and smoky, earthy flavor hold up well during cooking and truly shine in the final dish. If you prefer a milder mushroom flavor, classic white button mushrooms are a great alternative. For an even deeper umami, consider adding a mix of gourmet mushrooms like shiitake or oyster.
Potatoes: Cut into 1/2-inch cubes, potatoes are the hearty backbone of any gratin. Unpeeled red-skinned potatoes are recommended here for their thin skin, high moisture content, and ability to maintain their shape without becoming mushy. Yukon Gold potatoes are another superb alternative, offering a creamy texture and buttery flavor. For a more rustic feel, you can leave the skins on, ensuring they are thoroughly washed.
Kosher Salt: An important seasoning to enhance all the flavors. When substituting table salt for kosher salt, exercise caution: table salt is finer and denser, so use approximately two-thirds the amount specified for kosher salt to avoid over-salting.
Chicken Broth: This liquid gold helps to cook the potatoes to tender perfection and adds savory moisture to the gratin. Use your favorite prepared chicken broth or stock. If you’re lucky enough to have homemade chicken stock on hand, it will elevate the flavor even further. Vegetable broth can be used for a vegetarian version.
Cooking Spray: Primarily needed if you opt to transfer the gratin mixture to a separate baking dish instead of using an ovenproof skillet. As an alternative, you can grease the dish with a thin layer of oil or butter.
Shredded Swiss Cheese: Melts beautifully to create a golden, bubbly top. Swiss cheese offers a mild, nutty flavor that complements the other ingredients. For an even more intense, complex, and nutty profile, consider using shredded Gruyère cheese, known for its rich flavor that deepens with age. Other cheeses like sharp cheddar or a blend of mozzarella and parmesan would also be delicious.
Fresh Thyme Leaves: Chopped fresh thyme adds a distinctive, earthy, and slightly peppery flavor with subtle sweet and floral notes. It’s a classic pairing with potatoes and sausage, bringing an aromatic freshness to the dish. Feel free to use more for garnish after baking.

Mastering the Method: Step-by-Step Gratin Guide

While this recipe involves a bit of chopping, the hands-on time is rewarded with incredible flavor. The key to its simplicity is the use of a large ovenproof skillet, allowing you to transition seamlessly from stovetop to oven, minimizing dirty dishes.

Preheat your oven to 400°F (200°C). This ensures your oven is ready to go as soon as your gratin is assembled, promoting even cooking and a beautifully browned top.
Brown the Italian Sausage: Heat a large nonstick or ovenproof skillet over medium-high heat. Add the sausage, breaking it up with a spoon as it cooks. Sauté for about 5 minutes, or until it’s nicely browned and crumbled. This step is crucial for developing deep, savory flavors. Once browned, remove the sausage from the pan and set it aside, leaving any rendered fat in the skillet – it’s packed with flavor!

Pro Tip: An ovenproof skillet (like this one) is your best friend for this recipe, allowing you to do all the stovetop cooking and then transfer directly to the oven. This saves you from having to transfer the mixture to a separate baking dish later.

Sauté the Vegetables: Using the same pan with the leftover sausage drippings (or melt a little extra butter if needed), melt the butter. Add the chopped onion and sauté for 4 minutes, stirring occasionally until softened and translucent. Next, add the sliced mushrooms and continue to sauté for another 6 minutes, stirring occasionally, until they release their moisture and begin to brown. Finally, add the cubed potatoes and kosher salt. Sauté for 5 more minutes, stirring occasionally, until the potatoes start to brown slightly. This initial sautéing ensures the vegetables and potatoes are tender and flavorful before baking.

Make-Ahead and Storage Tips

This gratin is wonderfully forgiving and can be prepared ahead of time, which makes it an excellent choice for entertaining or busy weekdays. You can handle all the stovetop steps – browning the sausage and sautéing the vegetables – in advance. Once those steps are complete, simply set the skillet aside and let it cool. The gratin can then be finished in the oven just before your meal.

For even more convenience, I’ve successfully prepared the entire dish, assembled in the ovenproof skillet, and then refrigerated it overnight. The next morning, it was ready to go straight into the oven. Just be sure to allow an additional 10-15 minutes in the oven since the gratin will be starting from a chilled state. Leftovers store well in an airtight container in the refrigerator for up to 3-4 days and can be reheated in the oven or microwave.

Assemble and Bake: Once the potatoes are browned, stir the cooked sausage back into the pan along with the chicken broth. Remove the skillet from the heat. If you’re using an ovenproof skillet, simply top the mixture evenly with the shredded Swiss cheese. If you’re not using an ovenproof skillet, transfer the potato mixture into a 13 x 9-inch glass or ceramic baking dish that has been coated with cooking spray or butter, then sprinkle with cheese.

Sausage, Mushroom & Potato Gratin before baking

Sausage, Mushroom & Potato Gratin covered

Bake to Golden Perfection: Cover the skillet or baking dish and bake at 400°F (200°C) for 30 minutes. This initial covered baking allows the potatoes to become perfectly tender. Then, uncover and bake for an additional 15 minutes, or until the cheese is beautifully golden brown and bubbly, and the gratin is heated through.
Garnish and Serve: Finish by sprinkling with fresh thyme leaves just before serving. The aroma and flavor of fresh herbs truly elevate this dish.

Creative Variations to Make it Your Own

This Sausage, Mushroom & Potato Gratin recipe is a fantastic starting point, but don’t hesitate to put your own spin on it! Consider it a canvas for your culinary creativity:

Make it Heartier: For a more substantial meal, simply increase the amount of Italian sausage. You could also experiment with adding crispy bacon pieces or diced ham along with the sausage.
Vegetarian Delight: Easily transform this into a vegetarian dish! Omit the sausage entirely, double the amount of mushrooms (or add other hearty vegetables like bell peppers or zucchini), and swap the chicken broth for vegetable stock.
Spice It Up: If you love a bit of heat, opt for hot Italian sausage. Alternatively, stir in a pinch or two (or more!) of red pepper flakes with the onions, or a dash of cayenne pepper for a fiery kick.
Boost the Flavor: Introduce additional layers of flavor by adding some finely chopped red bell pepper or diced carrots to the skillet with the onions. For a richer, nuttier cheese flavor, replace the Swiss cheese with shredded Gruyère. You could also add a clove or two of minced garlic when sautéing the onions.
Herbal Twists: While fresh thyme is wonderful, feel free to experiment with other fresh herbs. Chopped fresh rosemary or sage pairs beautifully with potatoes and sausage. You could even use a combination of all three for a truly aromatic experience.
Add Some Greens: Stir in a few handfuls of fresh spinach or kale during the last few minutes of stovetop cooking, just before adding the broth. The greens will wilt down nicely into the gratin.

Time to Dig In – Your Sausage, Mushroom & Potato Gratin is Ready!

Once your gratin emerges from the oven, bubbling and golden, it’s ready to be savored. This dish truly shines at any meal, adapting seamlessly to your needs. For breakfast or brunch, pair it with a perfectly poached or fried egg and a fresh fruit salad. For dinner, it makes an outstanding side dish to roasted chicken, a juicy steak, or even baked fish. A simple green salad with a light vinaigrette provides a refreshing contrast to the richness of the gratin. No matter how you choose to serve it, this Sausage, Mushroom & Potato Gratin promises a satisfying and delicious experience.

5 from 1 vote

Sausage, Mushroom & Potato Gratin

Adapted from Cooking Light

Consider this the ultimate home fries in a casserole. Delicious medley of savory sausage, sautéed mushrooms and tender potatoes all done in one skillet – gratin style. A definite crowd-pleaser, naturally gluten-free, and perfect for brunch or dinner.

Prep Time 20 minutes

Cook Time 1 hour 5 minutes

Total Time 1 hour 25 minutes

Servings 8 – 10 servings

Author Rosemary Stelmach

Ingredients

8
ounces
mild Italian sausage, casings removed
2
tablespoons
butter
2
large onions, chopped
(4 cups / 16 ounces)
8
ounces
baby portabella mushrooms, sliced
3
pounds
red potatoes, chopped in 1/2″ cubes
1
teaspoon
kosher salt
1
cup
chicken broth or stock
cooking spray
(if needed)
1 1/2
cups
shredded Swiss cheese
(6 ounces)
2
tablespoons
chopped fresh thyme
(plus more for garnish)

Instructions

Preheat oven to 400°F (200°C).
Heat a large nonstick or ovenproof skillet over medium-high heat. Add sausage to pan, and sauté for 5 minutes or until browned, stirring to crumble. Remove sausage from pan and set aside, reserving any drippings.
Melt butter in the same pan. Add onion; sauté for 4 minutes, stirring occasionally. Add mushrooms; sauté for 6 minutes, stirring occasionally. Add potatoes and salt; sauté for 5 minutes or until browned, stirring occasionally.
Stir in the cooked sausage and chicken broth. Remove from heat. If using an ovenproof skillet, top directly with the shredded cheese. Alternatively, spoon the potato mixture into a 13 x 9-inch glass or ceramic baking dish coated with cooking spray; then top with cheese.
Cover and bake at 400°F (200°C) for 30 minutes. Uncover and bake an additional 15 minutes or until golden brown and bubbly. Sprinkle with fresh thyme before serving.

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