Use them for cupcakes or muffins. I think this is the original purpose. Besides tarts, I use mine to make frozen egg whites. It's easier than using an ice cube tray, especially when you only have one or two egg whites to freeze. I do this: Place one egg white into each silicone mold. Freeze. When frozen, pop the egg white into a plastic bag and store it in the freezer until needed. This beats freezing them in an ice cube tray all day (or saving them in the fridge where they don't stay fresh for long.)