Preheat the oven at 200ºC.
Beat the eggs and sugar for 1 minute. (Do not foam)
Melt the butter and Cacao Barry Guayaquil dark chocolate together in the microwave until it reaches 45ºC and add to the egg and sugar mixture.
Sieve the flour and baking powder and add into the chocolate mixture.
Grease the Pavoni "Muffin" mould with butter (optional) and add half the chocolate batter.
Remove the hardened pistachio filling from the freezer and unmould the fillings.
Add each of the pistachio fillings into the centre of each cavity. (On top of the chocolate batter)
Top each cavity with the remaining chocolate batter until you have filled all 10 cavities.
Bake in the oven at 200ºC for approximately 7-9 minutes.