Best Scalloped Potatoes Ever: Creamy, Cheesy, and Irresistible

Preheat your oven to 375°F (190°C).
Wash, peel, and thinly slice the potatoes. Aim for uniform slices about 1/8-inch thick to ensure even cooking.
Pat the potato slices dry with a paper towel to remove excess moisture.

In a medium saucepan, melt the butter over medium heat.
Add the minced garlic and sauté for 1-2 minutes until fragrant.
Whisk in the flour and cook for about 1 minute, stirring constantly, to form a roux.
Gradually pour in the warm milk and heavy cream, whisking continuously to avoid lumps.
Bring the mixture to a gentle simmer, then stir in 1 1/2 cups of cheddar cheese and 1/2 cup of Parmesan cheese. Continue stirring until the cheese is fully melted and the sauce is smooth.
Season with salt, pepper, and nutmeg (if using). Remove from heat.

Grease a 9×13-inch baking dish with butter or non-stick spray.
Arrange a layer of potato slices at the bottom of the dish, slightly overlapping each slice.
Pour a portion of the cream sauce over the potatoes, spreading it evenly.
Repeat the layering process (potatoes and cream sauce) until all ingredients are used, finishing with a layer of sauce on top.
Sprinkle the remaining cheddar and Parmesan cheese evenly over the top.

Cover the dish with aluminum foil and bake in the preheated oven for 40 minutes.
Remove the foil and bake for an additional 20-25 minutes, or until the top is golden and bubbly, and the potatoes are fork-tender.
Let the dish cool for 10 minutes before serving to allow the sauce to set.

Choose the Right Potatoes: Russet potatoes are ideal due to their starchy texture, which helps thicken the sauce.
Slice Evenly: Use a mandoline slicer for consistent slices, ensuring even cooking.
Warm the Milk: Adding warm milk to the roux prevents clumping and speeds up the sauce-making process.
Make Ahead: You can prepare this dish a day in advance. Simply assemble and refrigerate, then bake just before serving.