Step 1

Use a blender to whizz 300g of the strawberries to a purée, then sieve to remove the seeds. Make up the strawberry jelly according to pack instructions. When it’s ready, reserve 250ml of the jelly liquid, and put the rest into a 30cm x 20cm dish so it’s about 2cm in depth. Chill for 2-3 hours until set. Mix the reserved jelly liquid with the strawberry purée and keep covered at room temperature so it doesn’t set.

Step 2

When the first jelly in the dish has set, thickly slice the chocolate roll and layer in a deep trifle dish or glass bowl. Mix the cassis and sherry, and drizzle over the top. Quarter or halve the remaining strawberries, so they’re roughly the same size as the raspberries. Cut the jelly into cubes, then scatter the jelly and berries over the sponge, alternating layers as you do. Spoon over the custard then leave in the fridge for an hour.

Step 3

Very lightly whip the cream to soft peaks, then whisk in the reserved jelly and strawberry purée liquid until the mousse is thick but it still settles flat. Pour over the top of the custard and gently shake to even out the strawberry layer. Chill for at least 3 hours, then sprinkle with hundreds and thousands to serve.