Mix espresso powder with 8 tablespoons (approx. 80ml) of hot water (or if you have to go quickly or you don't have an espresso, you can also use normal cold coffee or coffee from the pod machine). Let cool down.
Finely grind the sponge fingers, drizzle with the espresso and let it steep for 15 minutes.
Mix the mascarpone, powdered sugar, vanilla sugar and Baileys with a whisk and add to the crumbs, stir everything well and shape them into balls (for me this will be about 35 pieces). Roll the balls in cocoa powder and store in a cool place.
If you prefer to have the balls firmer (because they stay soft, like with tiramisu) you can also add very soft 100g butter to the mass and then refrigerate for 30 minutes before shaping the balls.