Preheat your oven to 400°F (200°C).

In a large saucepan over medium heat, melt 4 tablespoons of butter. Add 3 cloves of minced garlic and 1 finely diced red onion. Sauté for 5 minutes until onions are soft.

Sprinkle in 1/4 cup of all-purpose flour and stir for 1 minute. Gradually whisk in 1 cup each of heavy cream and half and half. Cook for 3-4 minutes until thickened.

Mix in 1 cup of grated Asiago cheese, 1 tablespoon of freshly chopped rosemary, 1 teaspoon of smoked paprika, 1 teaspoon of ground sage, and season with kosher salt, black pepper, and freshly grated nutmeg.

Peel and thinly slice 2-3 medium sweet potatoes to about 1/8-inch thick.

Grease a 9"x13" baking dish with butter. Layer the sweet potato slices in a circular pattern, slightly overlapping.

Combine half of the Colby Jack cheese and half of the smoked Gouda cheese into the cooled sauce. Pour this over the layered sweet potatoes.

Cover with foil and bake for 45-50 minutes until sweet potatoes are tender.

Remove foil, sprinkle remaining cheeses on top, and bake uncovered for an additional 15-20 minutes until golden brown.

Let it rest for 10-15 minutes before serving.