Line baking trays and a 23cm springform tin with parchment.
Draw crown templates and 9cm lines on the parchment.
Whisk egg whites with 200g sugar until thick peaks form.
Beat yolks with remaining sugar and vanilla until pale.
Fold yolk mixture and sifted flour into the egg whites.
Preheat oven to 180°C.
Pipe a 23cm spiral base and crown shapes onto trays.
Dust with icing sugar and bake for 20 minutes.
Roast rhubarb with sugar for compote and bavarois at 180°C for 15 minutes.
Heat milk, vanilla, sugar, and half the cream to a simmer.
Whisk hot milk into egg yolks and thicken over heat.
Dissolve soaked gelatine into the warm custard.
Blend roasted rhubarb, sieve into custard, and add red dye.
Fold in whipped cream and cool in iced water until almost set.
Mix warm roasted rhubarb with dissolved gelatine for the compote.
Line the 23cm tin with savoiardi base and syrup-dipped fingers.
Glue crown pieces with fondant paste and spray with gold.
Layer compote, bavarois cream, and ginger jelly into the tin, chilling between each.
Remove the collar and top the russe with the finished crown.