Whisk egg yolks and sugar in a bowl until combined.
Bring milk and lavender to a boil in a pan.
Whisk the boiling milk into the egg yolks and return the mixture to the pan.
Add cream and cook until thickened without boiling.
Strain three-quarters of the custard over white chocolate, stir to melt, cool, and churn in an ice cream machine.
Chill the remaining quarter of the custard in the fridge.
Preheat the oven to 180°C.
Grate 40g of dark chocolate into a bowl.
Brush four ramekins with melted butter and dust with the grated chocolate.
Melt the remaining dark chocolate and butter over a pan of simmering water.
Stir ground almonds, egg yolks, and cornflour into the melted chocolate.
Whisk egg whites in a separate bowl until stiff peaks form.
Gradually whisk the caster sugar into the egg whites.
Fold the egg whites gently into the chocolate mixture.
Layer the mixture into ramekins with a chocolate truffle in the center of each.
Bake for 10 to 15 minutes until risen and slightly wobbly.
Plating with a spoonful of chilled custard, the fondant, cocoa powder, and lavender ice cream.