Sausage, Mushroom & Potato Gratin Recipe for Comforting Dinner

This versatile side dish works any time of day. Whether served with roasted chicken or alongside a couple of eggs for breakfast, this Sausage, Mushroom & Potato Gratin is reliably delicious.

It pairs beautifully with roasted poultry, complements a simple green salad, and makes a hearty brunch centerpiece. Simple swaps let you adapt the recipe to your tastes.

Ingredients for Sausage, Mushroom & Potato Gratin

Italian sausage – Casings removed. Mild works well; choose hot if you like more spice.
Butter – Salted butter is fine and convenient here.
Onions – Chopped. White, yellow, or sweet onions all work.
Mushrooms – Sliced cremini (baby portobello) are ideal for their meaty texture and deeper flavor; white buttons are a milder alternative.
Potatoes – Cut into 1/2″ cubes. Unpeeled red-skinned potatoes hold their shape well; Yukon Gold is another good choice.
Kosher salt – If substituting table salt, reduce the amount since it is finer and more concentrated.
Chicken broth – Use your preferred prepared stock or a homemade chicken stock if available.
Cooking spray – Only needed if transferring the mixture to a baking dish; oil or butter can be used instead.
Shredded Swiss cheese – Gruyère can be substituted for a nuttier, more pronounced flavor.
Fresh thyme leaves – Chopped; thyme adds an earthy, slightly peppery note with a subtle floral aroma.

Preheat the oven to 400°F.
Heat a large nonstick or ovenproof skillet over medium-high heat.
Add the sausage and sauté 5 minutes or until browned, breaking it up as it cooks.
Remove the sausage from the pan and set aside.

If you have an ovenproof skillet, you can complete the entire dish in that same pan.

Melt the butter in the pan.
Add the onions and sauté about 4 minutes, stirring occasionally.
Add the mushrooms and sauté about 6 minutes, stirring occasionally.
Add the potatoes and salt.
Sauté about 5 minutes or until the potatoes begin to brown, stirring occasionally.

This recipe requires a bit of chopping, but much of the work can be done ahead of time. Complete the stovetop steps, then refrigerate the skillet (or transfer to a baking dish) and finish in the oven before serving.

If prepared the night before, simply allow a few extra minutes in the oven since the dish will be chilled.

Stir the cooked sausage and chicken broth into the potato mixture, then remove from heat.
If using an ovenproof skillet, sprinkle the shredded cheese over the top.

Alternatively, spoon the mixture into a 13 x 9-inch glass or ceramic baking dish coated with cooking spray, then top with the cheese.

Cover and bake at 400°F for 30 minutes.
Uncover and bake an additional 15 minutes or until the top is golden and bubbly.
Sprinkle with chopped fresh thyme before serving.

Make it your own

This recipe is flexible—try these variations to suit your preferences:

Increase the sausage for a heartier dish.
Vegetarian option: Omit the sausage, add extra mushrooms, and use vegetable stock.
Want heat? Use hot Italian sausage or add a pinch of red pepper flakes.
More flavor: Add diced red bell pepper and swap Gruyère for Swiss.
Herb swaps: Replace thyme with chopped rosemary or sage, or combine them.

Ready to serve

Serve this gratin any time of day. It’s excellent with eggs for breakfast or brunch, pairs well with a green salad for lunch, and complements roasted chicken for dinner.