1-2 hours freezing time required
Pre-heat oven to 180ºC. Take 10 x frozen cookies out of the bag and place onto an oven tray lined with baking paper. Bake for 12-15 minutes and allow to cool completely.
Whilst cookies are cooling, take ice cream out of the freezer to soften slightly.
Scoop 2 heaped tablespoons of ice cream (60g) onto 5 of the cookies and top each one with another cookie.
Optional: Place cookie sandwiches onto a tray lined with baking paper and place into the freezer whilst melting the chocolate for the coating. In a heatproof bowl, melt the chocolate in the microwave in 30 second intervals, stirring until smooth. Take the cookie sandwiches out of the freezer (one at a time) and dip half the cookie into the melted chocolate.
Dip into the sprinkles or the crushed nuts. Place back onto the tray and into the freezer for 1-2 hours.
Pour the mixture into the prepared tin and carefully level the mixture with the spatula. Chop up your preferred frozen cookies into quarters and scatter over the top of the brownie mixture.
Place in the middle of the oven and bake for 40-45 minutes.
Remove tray from the oven, cool on a rack, then slice.