1.Preheat oven to 170°C/150°C fan forced. Grease a 20 x 30cm (base slice pan; line base and sides with baking paper, extending paper 2cm over long sides.
2.Stir butter and chocolate in a large saucepan over low heat until almost smooth. Remove from heat, cool for 10 minutes.
3.Stir sugars and eggs into chocolate mixture, then sifted flours and ¾ of the peanuts. Spread mixture into prepared pan. Drop slightly rounded teaspoonsful of peanut butter evenly over mixture. Push peanut butter into brownie mixture slightly with the back of a teaspoon. Sprinkle with remaining choc-coated peanuts.
4.Bake for 35 minutes or until firm and sides begin to come away from the sides of the pan. Cool in pan before cutting.
Choc-coated peanuts are often referred to as scorched peanuts. Sprinkle with a pinch of salt flakes after baking, if you like.Note