Preheat your oven to 400°F (200°C). Slice the gold potatoes into thin, even slices and arrange them in a single layer in a greased baking dish.

In a medium saucepan, melt the butter over medium heat. Add the minced garlic and sauté until fragrant, about 30 seconds.

Stir in the flour and whisk constantly for 1–2 minutes to create a smooth roux.

Gradually add the milk, whisking to avoid lumps. Cook until the mixture thickens slightly.

Add the salt, black pepper, and onion powder, mixing well to combine.

Lower the heat to medium-low and stir in the cheddar and mozzarella cheese until fully melted and smooth.

Pour the cheese sauce evenly over the sliced potatoes.

Cover the baking dish with foil and bake in the preheated oven for 40 minutes. Then, remove the foil and bake uncovered for an additional 20–30 minutes, or until the potatoes are tender and the top is golden brown.

For a crispier, more golden top, broil the dish for 2–3 minutes after baking.

Let the scalloped potatoes cool for a few minutes before serving. Enjoy!