First make the sponge. Heat your oven to 180C/350F/Gas 4. Grease and line the base of a 23cm/9in springform tin.
Put the eggs and sugar in a heatproof bowl and place over a pan of simmering water (don't let the bowl touch the water). Use an electric whisk to whisk them together until thick, pale and moussey and doubled in volume. The mixture should hold a trail when you lift the beaters out of the mixture. Take off the heat.
Fold the melted butter gently into the egg mousse, then gently fold in the flour. Pour into the prepared tin and bake for 15–20 minutes, or until cooked and lightly golden-brown. Leave to cool completely, then remove the sponge from the tin and peel off the parchment paper.
Line the sides of the same tin with baking parchment, first snipping a line of little ‘feet’ along the base of the paper so it will fit snugly against the base. Put the sponge base back into the tin.
To make the mousse, break up the jelly and put in a pan with a tablespoon of water. Melt gently over a low heat until smooth. Remove from the heat and set aside. Purée 200g/7oz of the strawberries in a blender until smooth and pass through a sieve to remove the seeds. Hull the remaining strawberries and cut in half top-to-toe (or slice into three if large).
Using an electric whisk, or a free-standing mixer with a whisk attachment, whisk the evaporated milk for at least five minutes, or until it is thick, bubbly and doubled in volume. Gently fold in the liquid jelly, then fold in the strawberry purée.
Arrange the strawberry slices around the edge of the lined tin, cut side against the tin. Scatter any extra strawberries over the sponge.
Pour the strawberry mousse into the tin, levelling the top. It doesn’t matter if the mousse doesn’t quite cover the strawberries. Place in the fridge for at least two hours to set.
To decorate, melt the chocolate in a heatproof bowl over a pan of simmering water. Dip a few strawberries in the melted chocolate and leave to set.
Pour the remaining chocolate into a paper piping bag. Snip the end off the piping bag and drizzle lines of chocolate over the top of the mousse (alternatively use a piping bag with a fine plain nozzle attached). Place the chocolate dipped strawberries in the centre and serve.