https://www.simplyrecipes.com/recipes/scalloped_potatoes/
Ingredients
3 tablespoons butter
2 pounds (about 4 medium sized) Russet potatoes, peeled, sliced 1/8-inch thick
1 large yellow or white onion, thinly sliced
2 tablespoons fresh parsley, chopped
1 tablespoon fresh chives, chopped (optional)
2 thick slices bacon, cooked and chopped
2 1/2 cups grated Swiss or Gruyere cheese (about 8 ounces)
1/2 cup grated Parmesan cheese (about 2 ounces)
2 1/2 cups to 3 cups half-and-half (half milk, half cream)
Salt and pepper