Go Back

Creamy Potato, Mushroom, and Spinach Gratin

A rich and comforting baked casserole featuring tender Yukon Gold potatoes, browned cremini mushrooms, and spinach in a savory garlic-parmesan cream sauce.
Print Recipe
Prep Time 25 minutes
Cook Time 1 hour 5 minutes
Total Time 1 hour 30 minutes
Servings: 6 Servings
Course: Main Course, Side Dish
Cuisine: American, French Inspired
Calories: 420
Ingredients Equipment Method Notes

Ingredients
  

Main Components
  • 2.5 lbs Yukon Gold potatoes peeled and sliced 1/4 inch thick
  • 3 tbsp unsalted butter divided
  • 1 lb cremini mushrooms sliced thickly
  • 5 oz fresh spinach roughly chopped
Cream Sauce
  • 1 shallot minced
  • 4 cloves garlic minced
  • 1.5 cups heavy cream
  • 0.5 cup vegetable or chicken broth
  • 1 tsp Dijon mustard
  • 0.25 tsp ground nutmeg
  • 1 cup parmesan cheese grated, divided
  • 1 salt and black pepper to taste
  • 2 tbsp fresh parsley chopped, for garnish

Equipment

  • Large skillet
  • 3-quart Baking Dish
  • Mandoline Slicer or Chef's Knife
  • Aluminum foil

Method
 

  1. Preheat oven to 375°F (190°C) and butter a 3-quart baking dish.
  2. In a large skillet, melt 2 tbsp butter. Brown the sliced mushrooms well. Add spinach and cook until wilted. Remove from pan and set aside.
  3. In the same skillet, melt remaining 1 tbsp butter. Sauté shallot and garlic until fragrant.
  4. Add heavy cream, broth, Dijon, nutmeg, salt, and pepper. Simmer gently. Whisk in 3/4 cup Parmesan until melted.
  5. Layer half the sliced potatoes in the baking dish. Top with half the mushroom-spinach mixture and half the cream sauce. Repeat layers.
  6. Cover tightly with foil and bake for 40 minutes.
  7. Remove foil, top with remaining 1/4 cup Parmesan. Bake uncovered for 20-25 minutes until potatoes are tender and top is golden.
  8. Let rest for 15 minutes before garnishing with parsley and serving.

Notes

Ensure fresh spinach is wilted, or frozen spinach is thoroughly drained of all water, to prevent a watery sauce. Do not rinse potato slices; their starch helps thicken the dish.