Boil the milk with the split vanilla pod and 60 g of sugar. Leave to infuse for 10 minutes covered. Soak 7 sheets of gelatin in cold water to soften them. In a saucepan, whisk the egg yolks with the remaining sugar. Add flour and cornstarch. Pour the milk after removing the vanilla. Bring to a simmer over low heat, stirring constantly. Remove from the heat, add the drained gelatin and leave to cool.
Line the sides of a cake tin with half-slices of oranges. Cut the sponge cake in 3 in the thickness. Put a layer of sponge cake in the mold, soak it with Cointreau mixed with 10 cl of orange syrup, spread a layer of cream and finish with the sponge cake.
Leave 2 hours in the fridge. Melt the apple jelly, add the 2 sheets of gelatin softened in cold water and drained. Cover the cake and leave to harden in the fridge for another hour.
Zest the kumquats with a vegetable peeler. Boil the remaining orange syrup. Dip the kumquat zest in it and simmer for 10 minutes. Unmold the cake and serve with the syrup and kumquat zest.
Chef Hubert's culinary ideas