Buttercream cake with vanilla custard

Last week a friend celebrated her birthday, but unfortunately that day I was busy and didn’t get to meet her to wish her a happy birthday in person and have a drink to celebrate. I tried to make it up by organizing a surprise fika together with another friend – the fika featuring Irish coffee and the delayed birthday cake I’ve been meaning to deliver at some point.

Since the birthday girl had really appreciated my buttercream in a cake I made last summer, I decided to go with buttercream again, also because this would give me plenty of opportunities for nice decorations. Swiss meringue buttercream is my favourite for piping decorations on cakes. I chose to keep the cake in the tones of white and blue, and thought about a nice basketweave all around, and the top all in flowers. All the outer decorations were made with Swiss meringue buttercream, I posted the recipe in this post – clearly this time there is no chocolate added, but some blue and green food colouring. To cover the whole cake I used 100 g of egg whites, 200 g of confectioner’s sugar and 400 g of butter; for the buttercream preparation directions, please refer to the post I linked before.

basketweave blue buttercream cake

This little afternoon party was hosted at my friend’s place – the other person who helped to organise it and provided the Irish coffee – and she happened to have this candle and candleholder that matched the cake just perfectly, so before the guests arrived I took the time to take some pictures of the cake with these props (including this wonderful white sheepskin).

basketweave blue buttercream cake basketweave blue buttercream cake

Inside, it’s gluten-free sponge cake with blue vanilla custard. Gluten-free flour made the sponge cake turn out quite white – whiter than it usually turns out when I bake with regular flour, thus contrasting even more sharply with the blue filling.

basketweave blue buttercream cake

Vanilla custard (filling for one cake):

  • 5 yolks
  • 150 g sugar
  • 65 g corn starch
  • 500 ml milk
  • vanilla

Bring 400 ml of milk to the boil in a large saucepan. In the meantime, beat the yolks with the sugar until light in colour and double in size. Beat in starch, vanilla (I used about 1/8 tsp of crushed vanilla bean) and 100 ml of cold milk. At this point, I have added my blue food colouring; if desired, this is when the colour can be added. When the milk in the saucepan has reached boiling temperature, lower the heat and pour in egg mixture, whisking by hand constantly. Keep whisking until the mixture thickens, lower the heat to the minimum if necessary, to prevent the cream from sticking to the bottom of the pan. Cook the mixture until it boils and the cream (which should already have thickened by then) will release large bubbles of air. Let cool completely before using in a cake.

blue vanilla custard

I usually fold a cup of unsweetened whipped cream into my custard before filling a cake with it: this way the cream has a more pleasant texture and the unsweetened whipped cream makes it a little less sweet. I like custard to be very sweet in pies, but in birthday cakes (especially if featuring also an outer frosting) it’s wise to keep the filling a little less sweet. There is no limit to the amount of whipped cream that can be folded in the custard, as long as it’s folded in gently and holds its firmness. This can be a useful way to yield more cream if one extra layer is to be featured in a cake!

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