For the cookie dough layer:
1. Whip together the butter, caster sugar, and brown sugar, in a stand mixer.
2. Next, crack in the egg and whip again until light and fluffy. It might look like the mixture has scrambled but don't worry, keep going.
3. Add in the dry ingredients and mix until you achieve a soft dough.
4. Fold in the chocolate chips. Mix again.
5. Press down into the bottom of a lined and greased brownie tin. Refrigerate for 30 minutes.
For the red velvet brownie layer:
1. In a stand mixer, beat the butter and sugar until light and fluffy, about 2 minutes.
2. Add the eggs and beat again. At this point it may look like the eggs have scrambled the butter mixture but don't worry. It will all come together once the dry ingredients have been added.
3. Next, add the flour, cocoa powder, baking powder and salt. Turn the mixer on low.
4. As the dry ingredients are being incorporated, pour in the milk.
5. Add in the food colouring and beat until the batter turns a beautifully-bright red.
6. Pour on top of the cool cookie dough base.
7. Place Ferraro Rochers on top.
8. Bake for 25 minutes. The brownies will have a slight wobble.
9. Allow to cool slightly before turning out onto a wire rack, remove the greaseproof paper and slice.