Place the custard powder and the sugar into a large bowl and add a little of the milk, stir until you have a smooth paste.
Heat the remaining milk in a large saucepan until it nearly reaches boiling point and pour in the custard powder mixture.
Stir continuously on a low heat until the custard thickens then set aside to cool.
To make the jelly, follow the packet instructions, but do not place it into the fridge to set.
Cut the Swiss rolls into equal slices and arrange them over the bases of two large deep baking trays.
Scatter the strawberries on top of the sponge. Pour the prepared jelly over the fruit. Cover the trays with cling film and leave to set in the fridge for about an hour and a half.
When the custard has cooled, gently pour on top of the set jelly.
Cover with cling film and return the trays to the fridge for a further 30 minutes, or until the custard is lightly set.
For the topping, lightly toast the almonds in a dry frying pan over a low heat for 2-3 minutes, or until golden-brown, keeping the almonds moving around the pan frequently to prevent them from burning. Set aside to cool.
Whip the cream until it forms soft peaks. Spoon the whipped cream over the custard. Scatter the almonds on top, cover and return to the fridge until ready to serve.