Prep: 1 hr
Freeze: 6 hrs
Cook: 15 min
Serves: 12

2 packs shop-bought brownie mix
150ml vegetable oil or butter
2 eggs
1.4 litres strawberry ice‑cream, softened
1 litre vanilla ice‑cream, softened
500ml chocolate ice‑cream, softened
Cocoa powder

Heat the oven to 180C/ 350F/gas 4. Line two baking trays with baking paper and line a large bowl with clingfilm.
Mix the brownie mix with the eggs, oil or butter, until just combined. Pour the mix into the baking trays and spread evenly. Bake according to the packet instructions, until the brownies are fudgy yet firm. Remove and leave to cool.
Once cool, cut one trayful in half lengthwise, then into eight equal rectangles. Leave four as they are, and cut the other four diagonally into eight triangles. Line the prepared bowl with these brownie pieces, covering the sides and bottom, and pressing down firmly, especially the seams, to create a shell with no gaps.
Scoop the strawberry ice-cream on to the shell and smooth with a spatula. Cover with clingfilm and press a medium-sized bowl into the ice-cream, so it rises up the sides and is flush with the top of the bowl. Freeze for three hours.
Unwrap, repeat with the vanilla ice-cream and freeze for another two hours.
Meanwhile, cut a circle into the other tin of brownie the diameter of the large bowl.
Uncover the now-frozen vanilla layer, fill with chocolate ice-cream, cover with the circle of brownie and freeze for one hour.
Carefully remove from the freezer and flip on to a serving platter. Leave a couple of minutes, then remove the bowl and dust with cocoa powder.