The filling for these cookies can vary, so feel free to get creative. Try different flavors of jam or marmalade.
Cinnamon is also used in some regions of Italy in this type of cookie, so if you like cinnamon, add 1/2 teaspoon to the dough.
If you have individual mini tart tins (about 1 3/4 inch in diameter), those can be used instead of mini muffin cups. Place the tins on a cookie sheet for baking.