Mix the chocolate and butter in a heatproof bowl and melt them together over a hot water bath. Remove from heat and let the mixture cool down.
Mix the eggs with sugar in a bowl and whip until triple in volume.
Stir in the vanilla extract then add the melted chocolate.
Fold in the flour, sifted with baking powder.
Add the chocolate and peanuts then place the batter in the fridge for 1 hour.
Spoon dollops of batter on a baking tray lined with parchment paper.
Bake the cookies in the preheated oven at 350F for 10-15 minutes, but not more. They're not supposed to dry out - in fact, they will be incredibly soft when you remove them from the oven.
Let the cookies cool in the pan.
Peanut Butter Frosting:
Combine the peanut butter, powdered sugar, softened butter and vanilla in a bowl.
Mix until fluffy, about 5 minutes, then stir in the cream and mix a few more minutes.
Fill the cookies, two by two, with a dollop of peanut butter frosting.