Crockpot Scalloped Potatoes

Ingredients (13)

• 2 3/4 cups Yukon Gold potatoes
• 2 3/4 cups sweet potatoes
• Kosher salt
• Freshly ground black pepper
• 4 tablespoons unsalted butter
• 1/4 cup finely diced yellow onion
• 1/4 cup all-purpose flour
• 2 cloves garlic
• 2 cups nonfat milk
• 1/4 teaspoon  freshly grated nutmeg**
• 1 cup freshly grated sharp cheddar cheese***
• 2 teaspoons chopped fresh thyme
• 1/4 cup freshly grated Parmesan cheese