Grease a pudding basin with butter and dust with flour.
Blend flour, sugar, butter, and baking powder in a food processor.
Add eggs while blending until a thick batter forms.
Place honey and grapes in the bottom of the basin.
Pour the batter over the grapes and cover with cling film.
Microwave on full power for five minutes until risen.
Whisk egg yolks and sugar together in a large bowl.
Heat cream, vanilla pod, and seeds in a saucepan until nearly boiling.
Cool cream for one minute then remove the vanilla pod.
Whisk the warm cream slowly into the egg yolk mixture.
Gently heat the mixture in the saucepan while stirring until thickened.
Invert the sponge onto a plate and serve with custard.