For an extra layer of flavor, try sautéing the apples in a tablespoon of butter before adding them to the sausage mixture. If you don't have fresh sage on hand, you can substitute 1 teaspoon of dried sage. Feel free to experiment with different types of cheese. Gruyere, mozzarella, or fontina would all be delicious in this strata. The strata can be assembled ahead of time and refrigerated overnight. Just add about 10-15 minutes to the baking time if baking from cold.