Garlic Parmesan Scalloped Potatoes

Name: Garlic Parmesan Scalloped Potatoes
Prep time: 15 min
Cook time: 1 h 15 min
Total time: 1 h 30 min
Cuisine: American
Ingredients: 4 tablespoons butter; 1 tablespoon minced garlic ((or 4 large garlic cloves, minced)); 4 tablespoons all-purpose ((or plain) flour); 4 cups milk ((skim, 2% or full fat -- more if needed)); 1 teaspoon chicken bullion powder ((or Kosher salt)); Salt (to taste); 1/2 teaspoon black pepper; 2 1/2 pounds (1 kg) Yukon Gold potatoes (or Russets) (peeled and sliced into 1/8-inch - 1/4-inch rounds); 2 cups shredded mozzarella cheese; 3/4 cup Parmesan cheese ((freshly grated)); 1 tablespoon fresh chives (divided)