Creamy Cheesy Potato Gratin Casserole Recipe

This cheesy potato gratin casserole is pure comfort: thinly sliced potatoes baked in a silky cream sauce and finished with a golden, bubbling cheese crust.

The rich, velvety texture and savory flavor make it an irresistible favorite for family dinners and special occasions.

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Recipe Information

• Prep Time: 20 minutes
• Cook Time: 1 hour
• Total Time: 1 hour 20 minutes
• Servings: 6

Ingredients

Simple ingredients deliver maximum flavor in this cheesy potato gratin casserole:

• 4 large russet potatoes, peeled and thinly sliced (about 1/8-inch thick)
• 1 1/2 cups heavy cream (or cashew cream for a dairy-free version)
• 1 cup whole milk or unsweetened almond milk
• 2 garlic cloves, minced
• 1 teaspoon salt
• 1/2 teaspoon freshly ground black pepper
• 1 teaspoon smoked paprika (optional)
• 1 1/2 cups shredded Gruyère cheese (or sharp cheddar)
• 1/2 cup freshly grated Parmesan cheese
• 2 tablespoons unsalted butter, cut into small cubes
• 1 teaspoon fresh thyme leaves (optional, for garnish)

Equipment Needed

• 9×13-inch casserole dish
• Mandoline slicer or sharp knife
• Medium saucepan
• Whisk
• Aluminum foil

Instructions

1. Preheat the Oven

Preheat your oven to 375°F (190°C). Grease a 9×13-inch casserole dish with butter or cooking spray so slices release easily after baking.

2. Prepare the Cream Mixture

In a medium saucepan, combine heavy cream, milk, minced garlic, salt, black pepper, and smoked paprika. Warm over medium heat, whisking occasionally until the mixture is steaming but not boiling. This gently infuses the cream with garlic and spices.

3. Slice the Potatoes

Use a mandoline or a sharp knife to slice the potatoes into even, thin rounds. Uniform slices ensure even cooking and a tender texture.

4. Layer the Potatoes

Arrange half of the potato slices in overlapping layers across the bottom of the prepared dish, packing them closely so the gratin holds together when sliced.

5. Add the Cheese and Cream

Sprinkle half of the shredded Gruyère and Parmesan over the first potato layer, then pour half of the warm cream mixture so it soaks into the layers.

6. Repeat the Layers

Add the remaining potato slices, then top with the rest of the cheeses and pour the remaining cream over the top, making sure all slices are coated.

7. Dot with Butter

Scatter the small cubes of butter over the top layer. The butter helps produce a beautifully browned, crisp finish.

8. Bake the Casserole

Cover the dish tightly with aluminum foil and bake for 45 minutes. The covered bake steams the potatoes until tender.

9. Finish and Crisp

Remove the foil and bake for another 15 minutes until the top is golden and cheese is bubbling. For a deeper crust, broil 2–3 minutes—watch closely to prevent burning.

10. Garnish and Serve

Sprinkle fresh thyme over the gratin if desired. Let the casserole rest about 5 minutes before slicing—this helps the layers set for clean serving.

Serving Suggestions

Serve this gratin alongside a crisp green salad or roasted vegetables. It makes a decadent side for roasted meats or a rich vegetarian main when paired with crusty bread.

Tips for Success

• Use starchy potatoes: Russet or Yukon Gold absorb the cream well and hold their shape.
• Cheese alternatives: Gruyère is classic, but sharp cheddar, Fontina, or Monterey Jack work nicely for different flavor profiles.
• Make ahead: Assemble up to a day in advance, cover, and refrigerate. Bring to room temperature before baking for even cooking.

Variations

• Dairy-free: Use cashew cream and vegan cheese.
• Herby: Add chopped rosemary or parsley to the cream for a fresh twist.
• Spicy: Stir in red pepper flakes or a pinch of cayenne for heat.

Storage and Reheating

Store leftovers in an airtight container in the refrigerator for up to 3 days. Reheat in a 350°F (175°C) oven to restore the crispy top, or use the microwave for a quick single serving.

Why You’ll Love This Recipe

This gratin is more than a side—it’s a luxurious combination of tender, creamy potatoes and a cheesy, golden crust. Easy to prepare and highly versatile, it’s a recipe you’ll return to for holiday meals and weeknight comfort alike.

Cheesy Potato Gratin Casserole

• Author: Mila
• Prep Time: 20 minutes
• Cook Time: 1 hour
• Total Time: 1 hour 20 minutes
• Yield: 6 servings
• Category: Side Dish
• Method: Baking
• Cuisine: French
• Diet: Vegetarian