Potatoes au Gratin with Asiago Cheese and Sage

Ingredients

• Preheat the oven to 400°F. Lightly grease a 9"x13" oven-safe baking dish.
• Prepare the potatoes by washing, peeling, and thinly slicing them with a mandoline into 1/8" thick slices.
• 2-1/2 lbs Yukon Gold potatoes, peeled and, thinly sliced with a mandoline
• 6 tablespoons unsalted butter, divided
• 2 yellow onions, diced
• 5 cloves garlic, minced
• 2 tablespoons all-purpose flour
• 1 cup half-n-half
• 3/4 cup whole milk
• 1/4 teaspoon freshly grated nutmeg
• 1/4 teaspoon Kosher salt
• 1/8 teaspoon black pepper
• 1-1/2 cups freshly grated Asiago cheese, divided
• 10-12 sage leaves, finely chopped, divided
• 1/2 cup bread crumbs