Garlic Frittata

8 eggs
1/2 cup milk
1/2 cup Parmesan cheese, grated
2 tablespoons butter
4 cloves fresh garlic, minced
1/2 cup onion, chopped
4 ounces Polish sausage, chopped
4 potatoes, shredded
4 ounces shredded Cheddar cheese

Beat together the eggs, milk and Parmesan cheese; set aside.

In a large skillet over medium-high heat, melt butter and saut