Preheat the oven to 190C and line a 30 x 40cm baking tray with greaseproof paper or a silicone mat.
Put the eggs and sugar in the bowl of a stand mixer, place a small amount of water in a pan and bring to a slow boil. Place the bowl over the bain marie and whisk until it reaches 37C.
Remove the bowl from the heat and using the whisk attachment, whisk until the eggs reach a ribbon stage. This means the mixture forms a trail and sits on top of the mixture before sinking in.
Fold in the flour and when it is nearly all folded in, take a couple of spoonfuls of the mixture and mix it with the melted butter.
Return this to the rest of the mixture and fold through until it is fully incorporated.
Pour the mixture into the baking tray and spread out evenly with a stepped palette knife.
Bake in the oven for 12-15 minutes until golden brown and the sponge springs back when touched gently.
To make the kirsch syrup combine all of the ingredients in a saucepan except for the kirsch and bring to a boil. Simmer for 2-3 minutes and allow to cool. Once cool add the kirsch and stir.
To make the mousse, whisk the egg yolks and sugar together in a large bowl until they become light in colour (2-3 minutes).
Place the chocolate feves in a large bowl, if using a bar of chocolate, chop it into small pieces.
put 150ml of the cream in a saucepan with the milk. Bring to a boil. Add half the hot mixture to the eggs and mix thoroughly.
Return all of this to the pan and heat until the mixture coats the back of a spoon, sieve the liquid onto the chocolate and mix until the chocolate is melted and emulsified. Leave to cool a little.
Put the remaining cream in the bowl of a stand mixer and whip until stiff peaks have formed.
Gently fold the whipped cream into the melted chocolate until completely mixed. Use the mousse immediately, you don't want to let it set.
To make the ganache icing put the cream, caster sugar and liquid glucose in a saucepan and bring to a boil.
Put the chocolate in a bowl and pour the hot cream mixture onto the chocolate in batches. Stir until the choocate and cream are combined. Leave the ganache to cool and store in a tupperware container until you are ready to use it. This can be made up to 4 days in advance.
Cut out a piece of genoise using the 20cm entremet mould, use another mould or cake tin to cut out an 18cm circle. Place the larger piece of genoise in the bottom of the mould, spoon a third of the mousse on top and use a palette knife to spread it up the sides of the tin.
Place the smaller piece of genoise on top of the mousse and then add the jam, being careful to keep it on the cake and not in the mousse.
Take the remainder of the mousse spoon it on top of the jam, using a stepped palette knife smooth the mousse so that it completely fills the mould and is flat on top.
Place the cake in the freezer and leave to freeze for at least 4 hours.
Place the frozen cake on a cake rack over a baking tray. Using a chef's blowtorch heat the sides of the entremet ring to remove the ring and slide it off.
Take the ganache glaze and warm it in the microwave until it reaches 35-40C and then pour this on top of the cake. Using a stepped palette knife spread the ganache to cover the top of the cake and the sides. You will need to work quickly as the ganache will set against the frozen cake.
Once the ganache icing has set, move the cake to a cake stand or plate and tidy up the edges with remaining ganache if necessary.
Decorate with the kirsch cherries by piping blobs of the ganache on the bottom as glue and place in the fridge to thaw before eating.