Preheat the oven to 180°C . 

1. Melt the butter and the chocolate in a bain-marie. 
   1. Put a saucepan on a medium heat and fill it with water
   2. Place a bowl in the saucepan. Make sure the bowl completely seals the cooking pot to prevent steam from escaping. 
   3. Gently stir together the butter and chocolate until completely melted. 
   4. Be careful not to boil your water, the bowl should get hot from the steam.
2. Break the eggs into a mixing bowl and beat until fluffy.
3. Add the Zùsto to the eggs and mix well until you get a foamy mixture (at least 10 minutes in the food processor)
4. Sift the flour, cocoa powder and baking powder over the eggs and mix well until the mixture is smooth and even.
5. When the chocolate and butter are completely melted, add them to the mixing bowl.
6. Mix everything together well and add a pinch of salt. 
7. Prepare the baking tin: Grease with butter/vegetable oil, add flour or breadcrumbs for a crispy crust. 
8. Pour the batter into the baking pan and flatten it.
9. Bake the mixture for about 25 minutes in an oven at 180°C. 

Tip: Check to see if the brownie is done by piercing it with a skewer. If there is any wet dough sticking to the skewer, they will need to cook in the oven for a few minutes longer. Brownies may remain soft and moist on the inside but should be cooked.