Corned Beef and Potato Cheese Bake without bread

1 (10 ounce) can refrigerated prepared pizza crust 1/2 lb corned beef , cut into 1/2 inch cubes 1 tablespoon butter 1/2 chopped onion 1 1/2 cups frozen[...]

5 large baking potatoes , peeled, and cut into cubes 1/3 cup sour cream (low-fat is okay) 1/4 cup milk (1% is okay) salt and pepper 2 tablespoons oil 5 cups[...]