Pre-heat your oven to 180°c (or 160°c for a fan-assisted oven or Gas Mark 4) and line a 20cm x 20cm tin with greaseproof paper. Set aside. In a large bowl, sift the flour, baking powder, salt, cocoa powder and sugar together.
Add the butter/margarine and eggs to the dry ingredients, and mix until combined to a batter.
Roughly chop the Kinder Chocolate and add to the batter, stirring in until evenly distributed.
Pour into your pre-lined baking tray, ensuring the batter is right to the edges. Bake at in your pre-heated oven for 25 minutes, until it looks dry and top and they edges are slightly crispy.
Once baked and removed from the oven, allow to cool for 10 minutes before crumbling your Kinder Eggs over the top whilst still warm. Allow to cool completely before cutting into your desired sized brownies.