Pre-heat oven to 180°C

Grease and line a 9"x9" brownie pan

Cream the butter and sugar together until fluffy

Add the eggs one at a time and mix well after each one

In a seperate bowl sift together the Yorkshire Pudding batter mix, cocoa powder and baking powder

Gradually add the dry ingredients to the creamed meixture

Spread the batter into the prepared pan and level out

Bake at 180°C for 30 minutes

Check by inserting a knife into the middle to see if the middle is cooked. If so take out of the oven. If not leave in for a couple more minutes

Cut into squares whilst in the tin then leave until completely cool before sprinkling with icing sugar if desired.