2 tablespoons butter, plus more for greasing baking dish
1/2 white onion, minced
2 garlic cloves, minced
1 1/2 teaspoons salt
1/2 teaspoon freshly ground black pepper
1/2 cup chicken stock
1 1/4 cups heavy cream, plus more if needed
1 1/2 lbs russet potatoes, peeled and sliced 1/8-inch thick
2 cups cheddar cheese, grated
3/4 cup provolone cheese, grated
1/2 cup Parmesan cheese, grated
Fresh parsley, chopped, for garnish
Preheat oven to 425°F and grease an 8×8-inch baking dish with butter.
In a large pot over medium heat, melt the butter. Add onion and cook until soft and translucent, about 5 minutes. Add garlic and season with salt and pepper and cook 30 seconds more.
Stir in stock, cream, and potatoes and bring to a low simmer, but do not boil. Cover and reduce heat to medium-low. Let cook until potatoes are tender, 15-20 minutes. Adjust seasoning as needed.
Transfer mixture to baking dish, top with cheese and bake until bubbly and cheese has melted, 10-15 minutes.
Serve garnished with parsley, if desired. Enjoy!