Mix the vanilla custard powder with the sugar and some of the banana nectar until smooth.
Heat the remaining banana nectar in a saucepan.
Whisk in the dissolved custard powder.
Stir until it comes to boil and thickens.
Transfer to another recipient, cover the pudding with cling film (directly on the surface) and leave to cool.
Sift the flour, cocoa powder, baking powder and baking soda into a bowl.
Mix both sugars, salt and cinnamon to the flour.
Melt the butter.
Mash the bananas. (e.g. with a fork)
Stir the buttermilk, vanilla extract and eggs into the melted butter.
Add the butter mixture and mashed bananas to the flour and mix.
Pour the batter into prepared muffin tins. 12 muffins.
Bake in the preheated oven at 200°C for about 25 minutes. Test with a stick.
Leave to cool on a rack.
Mix the mascarpone, vanilla extract, icing sugar and 4 tbsp of the cold custard briefly until smooth.
Pour in the whipping cream while stirring.
Add the cream stiffener or San-apart and whip until stiff.
Put to chill briefly in the refrigerator.
Hollow out the muffins carefully, for later use. The best way is to use an apple corer or a small spoon.
Put the banana custard into a freezer bag (cut off the tip) and pipe into the muffins.
Put the small "lid" back on.
Fill the Banana Mascarpone Cream into a piping bag with a star-shaped nozzle.
Pipe the cream onto the muffins.
Decorate with banana chips and grated chocolate. (It is best to grate the chocolate directly onto the cupcakes with a peeler).
Chill until ready to serve.