In a mixing bowl, cream butter and sugar on medium speed for 10 minutes
Incorporate one egg at a time, beat well between each addition, you might want to add only 1 teaspoon of flour to the wet mix.
Fold in the sifted flour, cocoa, baking soda, baking powder and salt. Do not over beat, just incorporate gently until full absorption
Add the chocolate finely chunked to the batter, give it a stir.
Preheat the oven at 175C. Prepare a loaf tin, butter and cover with a parchment paper. pour the batter oven the tin and bake for 35 minutes or until you insert a stick and it comes out perfectly dry. Remove cake for the oven, let it rest 10 minutes in the tin then unmold on a rack until totatlly cool.