Step 3: Bake tiny Cakes
When they're done, close the lids on 'em. They're self-sealing, and you'll be able to see the seal forming!
Alternatively, you can add a chocolate ganache* to the top before sealing. Make sure to screw those caps on while the cakes are still hot though, to get that all-important seal.
* To make ganache: Heat 1 cup cream in a small sauce pan over medium heat. Bring just to a boil, watching very carefully because if it boils for a few seconds, it will boil out of the pot. When the cream has come to a boil, pour over 9oz chopped chocolate, and whisk until smooth. Allow the ganache to cool slightly before pouring over cake.