The chocolate must be grated on a large grater, or if you have it you can put it in a blender, I did it to grind it.
In a saucepan, melt the butter and when it is completely melted, put the chopped chocolate, cocoa on top and mix until it is homogeneous and you get a fine cream.
In a bowl, beat the eggs well with the mixer, until they froth, then put the sugar in 2 tranches, mixing well with the mixer, in order to aerate the eggs. or aerated. After the sugar has melted, add the chocolate cream with butter over the eggs, pour it lightly on the edge of the bowl so as not to spoil the air bubbles of the eggs, then add the flour and mix gently from the bottom up with a spatula.
I broke half of the amount of biscuits into pieces and incorporated them into the dough, I put the other half on top after I put the dough in the tray.
I put the cake in the oven for about 40 minutes, but it depends on what oven you have, so it's better to check with the toothpick if the cake is baked or not. Optionally you can sprinkle with powdered sugar… but I didn't .
The quantities I use in this recipe are for a large tray, so if you have a normal tray, you can halve all the quantities.