Once the hazelnuts are cool enough to touch, roll around in your hands or in a towel to remove the dark brown skins. Some of the skins will stick on the nuts and that’s OK.
Food process the hazelnuts with vegetable oil until they form a thick paste.
In a medium-sized mixing bowl, mix together sugar, flour, baking powder, baking soda, salt, instant coffee, and butter until fully combined.
Mix in hazelnut paste.
Mix in eggs, one at a time.
Mix in milk.
Fill cupcake liners 2/3 full.
Bake for 20 minutes or until a toothpick inserted into the center of a cupcake comes out clean.
Frosting Directions:
In a medium-sized mixing bowl, whip butter until light and fluffy.
Mix in mascarpone and vanilla.
Mix in powdered sugar a little bit at a time.
Spread or pipe on cooled cupcakes.
Optionally top with finely chopped toasted hazelnuts.