Low Sodium Swiss Potatoes Au Gratin

Name: Low Sodium Swiss Potatoes Au Gratin
Prep time: 20 min
Cook time: 1 h
Total time: 1 h 20 min
Cuisine: American
Ingredients: 4 large russet potatoes (thinly sliced (I used a mandolin for this)); 1 medium onion (peeled and sliced thinly (I used a mandolin for this)); 1 1/2 cups grated Swiss cheese (divided into 1 cup and reserve a half cup for the topping); 3 Tbsp unsalted butter; 3 Tbsp all-purpose flour; 1 tsp black pepper; 1 tsp garlic powder (salt free); 1 1/2 cups 2% milk