Preheat the oven to 180°C.
Add peanut butter and eggs to a bowl and mix well.
Add erythritol, almond flour, and baking powder, and mix until combined.
Chop the dark chocolate and mix it into the batter.
Pour the batter into a baking pan and smooth the surface.
Top with the remaining dark chocolate and bake for 20 minutes.
Let it cool completely, then cut into desired portions.