Scalloped Potatoes

Bahan-bahan (10 porsi)

• 3 tablespoons butter
• 1 small white or yellow onion, peeled and thinly sliced
• 4 large garlic cloves, minced
• 1/4 cup all-purpose flour
• 1 cup chicken stock or vegetable stock
• 2 cups whole milk (or half and half)
• 1 1/2 teaspoons Kosher salt
• 1/2 teaspoon black pepper
• 2 teaspoons fresh thyme leaves, divided
• 4 pounds Yukon Gold Potatoes, sliced into 1/8-inch rounds
• 2 cups freshly-grated sharp cheddar cheese*, divided (feel free to add more cheese if you’d like)
• 1/2 cup freshly-grated Parmesan cheese, plus extra for serving