Step 1

Preheat your oven to 425°F (220°C) and grease an 8x8-inch baking dish with butter.

Step 2

In a large pot over medium heat, melt the butter. Add the minced onion and sauté until soft and translucent, about 5 minutes. Stir in the garlic, salt, and black pepper, cooking for an additional 30 seconds.

Step 3

Pour in the chicken stock and heavy cream, then add the sliced potatoes. Stir gently to combine. Bring the mixture to a low simmer (avoid boiling). Reduce the heat to medium-low, cover the pot, and cook until the potatoes are tender, about 15-20 minutes. Adjust seasoning to taste.

Step 4

Transfer the creamy potato mixture into the prepared baking dish. Sprinkle evenly with cheddar, provolone, and Parmesan cheeses.

Step 5

Bake in the preheated oven until the cheese is melted, bubbly, and golden brown, about 10-15 minutes.

Step 6

Remove from the oven and let cool slightly. Garnish with fresh parsley, if desired, and serve. Enjoy!