Grease and line the base and sides of the cake tin with greaseproof paper.
Mix together the butter and sugar, then beat in the vanilla and eggs. Sieve in the flour and cocoa powder then mix to combine. Pour into the tin and level the top. Set aside in the freezer to firm up for 15 minutes.
CARAMEL LAYER & COOKIE DOUGH
Remove the brownie from the freezer then spread over the caramel sauce in an even layer. Return to the freezer for another 10 minutes.
In a large bowl cream together the butter and sugar. Beat in the egg and vanilla and then stir in the flour, bicarbonate of soda and the chocolate chips.
Remove the brownie tin from the freezer and spread over the cookie dough.
Bake for 35-40 minutes then remove from the oven and allow to cool completely in the tin.