For a richer flavor, consider using a combination of sweet and sour cherries. If you don't have removable-bottom tart pans, you can use muffin tins instead. Adjust baking time accordingly. Feel free to experiment with different extracts, such as vanilla or lemon, to customize the flavor of the tarts. The tarts can be stored in the refrigerator for up to 3 days. If the crust starts to brown too quickly, you can tent the tarts with foil during the last 10 minutes of baking.