Vanilla ice cream and salted caramel choc-chip cookie dough sandwiches

Grease and line the base and 2 opposite sides of a 25cm square brownie tin with baking paper. Do this by cutting a piece of baking paper into a rectangle of about 40cm x 24cm, covering the base and going up 2 facing sides with the baking paper (lining these sides will allow you to pull out the slab of ice cream sandwiches by the paper overhang, once the sandwiches are frozen).

For the cookie dough, put the softened butter and castor sugar in a bowl and, using an electric mixer, beat until pale and fluffy. Add the 5ml (1 tsp) vanilla essence and a pinch of salt, and beat again to combine. Fold in the flour and chocolate chips or chunks until just combined, and a dough forms.

Divide the dough in 2 and, using your fingertips, press ½ of the cookie dough firmly and evenly into the base of the lined tin. Smooth the dough with the back of a dessertspoon. Pop the tin into the freezer for the time being.

Between 2 pieces of baking paper, roll the remaining ½ of the cookie dough into a 25cm square, using a rolling pin. Peel off the top layer of baking paper and trim the edges of the dough with a knife to create a perfect square. Carefully replace the top layer of baking paper and transfer this piece of cookie dough (still between the baking paper sheets) to the freezer to firm up.

For the salted caramel layer, place the Nestlé Caramel Treat, 10ml (2 tsp) vanilla essence and 2,5ml (½ tsp) salt in a medium-sized bowl, and whisk gently until the caramel is smooth and lump free. Remove the cookie dough-lined tin from the freezer, transfer the smooth caramel to the tin and spread into an even layer over the cookie dough. Return the tin to the freezer.

For the ice cream layer, remove the store-bought vanilla ice cream from the freezer and transfer it to a bowl. Allow to soften at room temperature, about 10 minutes, before stirring until smooth. Remove the cookie dough-lined tin from the freezer, transfer the ice cream to the tin and spread evenly over the caramel layer. Peel the baking paper off the frozen 25cm cookie-dough square and place the square on top of the ice cream layer, gently pressing it onto the ice-cream layer. Return the tin to the freezer to firm up, 4 hours or overnight.

To slice, remove the frozen slab from the tin by running a knife around the edge, then lifting it out by the overhanging baking paper and placing the slab on a cutting board. Dip a sharp knife into boiling water to aid cutting and slice into 25 ice-cream sandwiches of about 5cm squares each. Stack the sandwiches in the tin, wrap in cling film and store in the freezer until ready to serve.