Pre-heat the oven to 180°C and line and grease a 20cm square tin.
Whisk together the chocolate, sugar, and eggs, and then fold in the flour. Pour into the greased lined tin.
Swirl the dulce de leche on top, sprinkle with peanuts and bake at 180°C for 25 to 30 minutes. Cool in the tin, and then cut into 8 squares.