Preheat the oven to 350°F and line an 8 x 8-inch baking pan with baking paper.
With an electric mixer, whisk together the avocado, with the eggs, butter, Erythritol, to get a smooth and lump-free batter.
In another bowl, combine the dry ingredients: the cocoa powder with the almond flour, salt and baking powder. Whisk well.
Fold the dry ingredients mixture into the avocado batter.
Add 4 tablespoons of the chopped chocolate and stir.
Pour the batter into the prepared baking pan and sprinkle the remaining chocolate on top.
Bake for about 20 minutes and allow to reach room temperature before cutting and serving.