Cookie Cake:

1. Preheat oven to 175C/347F.

2. Line the inside of a 23cm/9-inch springform cake tin with baking paper. 

3. In a medium bowl, sift the flour, baking soda, cornflour, salt and mixed spice and stir together. 

4. In a large bowl, add the butter and both sugars. Whisk until smooth.

5. Add in the egg and vanilla, and whisk again until smooth. 

6. Add in the dry ingredients. First fold in until just combined, then add the milk and whisk until a thick cookie dough is formed.

7. Fold in the chocolate chips leaving a few for top decoration. 

8. With your hand, press the cookie dough into the bottom of the cake tin and press in a few of reserved chocolate chips on top for decoration. 

9. Bake in oven for 25 minutes, until top is lightly golden and a  toothpick inserted in the middle comes out clean. 

10. Leave to cool completely in the tin then remove. 

11. When the cookie cake has completely cooled, top with piped buttercream and decorate with chocolate chips and funfetti sprinkles.

Buttercream:

1. In a large bowl, add the butter and beat until smooth. 

2. Sift in the icing sugar, add the vanilla essence, salt and milk and beat again until smooth. 

3. Spoon buttercream into a piping bag with star nozzle. Pipe around the edge of the cookie cake with smaller pipings on the inside. 

4. Decorate. 

5. Enjoy!