Cookie Cake with Chocolate Frosting

I made this cake as a prize for the class at school who returned all their library books first! Bribery works!! It was so delicious and the kids all loved it.

Cookie Cake with Chocolate Frosting
(from Good Food Magazine October 2015 and Sally's Baking Addiction)
(Serves 8-10)

175g unsalted butter, softened
200g light soft brown sugar
1 egg, plus 1 yolk
2 tsp vanilla extract
250g self-raising flour
2 tsp cornflour
2 tsp baking powder
100g milk chocolate chips
50g white chocolate chips

For the frosting:
210g icing sugar
32g cocoa powder
115g unsalted butter, softened to room temperature
2 tbsp double cream
1 tsp vanilla extract
salt, to taste

Preheat the oven to 200C and grease a 22cm springform cake tin.

Beat the butter and sugar in a large bowl until pale and fluffy, then mix in the egg, egg yolk and vanilla.

Combine the flour, cornflour and baking powder, then fold into the butter mixture until fully incorporated – it will be quite thick.

Add the chocolate chips and mix until evenly distributed. Spoon the mixture into the prepared tin and bake for 20-25 mins or until light golden brown. Leave to cool for 5 mins.

Whilst the cake is cooling make the chocolate frosting. Beat the butter with a hand held mixer on a medium speed until creamy - about 2 mins. Sift the icing sugar and cocoa powder into the bowl alternating with the cream and vanilla. Beat on a low speed after each addition. Once it is all added, beat on high speed until creamy and combined for at least 2 mins. Add a pinch of salt if the frosting is too sweet. Decorate the cooled cookie cake with frosting. Cut into slices and serve.