Mix together eggs, cocoa powder, salt, baking powder, instant espresso, and vanilla.
In a separate bowl cream butter and sugar, then microwave gradually (15 sec at a time) until sugar dissolves and is shiny.
Combine the egg and butter mixtures well, then add flour and mix gently, do not overmix.
Pour half the batter into a 9x9 baking dish, then cover with melted nutella and 7 chopped ferrero rochers.
Top with remaining batter.
Bake at 350 for 28-32 min.
Once its out of the oven, top with the rest of the ferrero rochers!
Optional: drizzle on some more melted nutella
