• Preheat the oven to 180ºc / 350ºf / Gas 4.  Place cup cases on 2 12 hole cake /Yorkshire tins, will help to keep perfect round cakes.
• In a bowl, mix together the margarine and caster sugar until light and fluffy.
• In a separate bowl, beat the eggs and add the vanilla extract.  In another bowl add the flour and baking powder.
• Sift a third of the flour in the butter mixture and combine, add the egg and stir together.  Alternate until all combined.  Pour in the chocolate chips and stir.
• Divide the mixture up into the case cases.
• Bake in the oven for 25mins, or until golden (see tip).  Leave to cool.

Top tip:

• If you press in the middle of the cake and it bounces back up it's cooked.