Boston Cream Cupcakes

 Boston Cream Pie involves a cake being filled with custard and topped with chocolate frosting. This is a cupcake version as found in the awesome Hummingbird Bakery: Cake Days book. The vanilla sponge, which is very moist, is filled with a thick vanilla-infused custard - if that wasn't enough, there's another element to this masterpiece. Chocolate Frosting. Very rich and chocolaty, you could eat this as a dessert on it's own. It does use a lot of cocoa powder but it's worth it; the generous quantity of frosting means there are no scarce scrapings on the cakes - and what's even better is that you may have some left over. There's no shame in eating it with a spoon like I did. 

Boston Cream Cupcakes
(Hummingbird Bakery: Cake Days)
for the sponge:
80g unsalted butter, softened
280g caster sugar
240g plain flour
1 tbsp baking powder
1/4 tsp salt
240ml milk
2 large eggs
1 tsp vanilla essence


for the filling:
250ml milk
1/2 tsp vanilla essence
2 large egg yolks
50g caster sugar
1 tbsp plain flour
1 tbsp cornflour


for the frosting:
400g icing sugar
100g cocoa powder
160g softened butter
80ml milk


Preheat the oven to 190C. Line a muffin tin with cases - you'll need 12-16. With an electric mixer, mix the butter, sugar, flour, baking powder and salt on a low speed until mixture resembles fine breadcrumbs. Put the remaining sponge ingredients in a jug and whisk by hand to combine. Pour three-quarters of this mixture into the batter and mix until combined. Add the remaining liquid and increase the speed until mixture is smooth. Fill cases two-thirds of the way up. Bake for 18-20 minutes until well risen and springy to the touch. Cool completely. 
Make the custard filling - Heat the milk and vanilla and bring to a boil. Meanwhile, whisk remaining ingredients together by hand in a bowl until smooth and well combined. Once milk is boiling, remove from heat and pour 4-5 tablespoons into the egg yolk mixture to loosen, then return this mixture to the hot milk in the pan. Stir to incorporate then return to the heat , whisking constantly to prevent lumps. Boil for at least one minute so flour is cooked properly. When thickened, pour into a bowl and cool completely for 30-40, covering with cling film to stop a skin forming. 
Make the frosting: Slowly beat together the icing sugar, cocoa powder and butter until sandy in texture. Pour in the milk gradually and whisk until soft and fluffy.
Using a sharp knife, make a hole in the centre of each cupcake about 2cm in diameter and 3cm deep, reserving scooped out sponge. Pipe/spoon custard into centres then replace sponge lids. Spread or pipe with chocolate frosting.