Rhubarb Crumble Cake with Custard Buttercream

My friend Martina regularly posts pictures of cake to my Facebook timeline with the caption “yuuuuuuummmmmmm”. Over the years I have come to understand that this is code for “PLEASE MAKE THIS FOR ME”. Occasionally, on the principle of “treat ’em mean to keep ’em keen”, I oblige. Actually, I would oblige more often but Martina and her husband Josef are so busy, I feel like I would be risking baking in a vacuum. To coin a phrase.

Rhubarb Crumble Cake with Custard Buttercream

Anyway, that’s how my Rhubarb Crumble Cake with Custard Buttercream came into being. I needed a pair of riding gloves for an upcoming horseback excursion (Martina sells awesome European riding gear), and with the leverage of this cake, I managed to land a visit to the shop and a dinner invite.  The Rhubarb Crumble Cake was intended to be a shameless copy of a recipe Martina found on www.homefarmer.co.uk, but I confess that I adapted and embellished the recipe somewhat. It’s funny, when people do that to my recipes I feel a bit affronted, yet I find myself free to do this. Double standards? Not really, its just that sometimes recipes don’t look quite right: like the original batter looked too gluggy, and the crumble looked too plain, and the buttercream had too much icing sugar, so would be too sweet… that sort of thing. In my defence I also knew that my dinner party audience included a German and an Austrian, neither of whom are of the “American School” of sickly sweet cakeophiles. With due respect to David Bowie, who might have said otherwise, I think with baking you have to play to your audience (rather than your art) if you want to be adored.

Rhubarb Crumble Cake with Custard Buttercream

I’m sticking to my adaptation guns with this one because, not to put too fine a point on it, this cake is SUPERB. Moist and studded with pink jewels of rhubarb, sandwiched with light, salty-sweet custard powder buttercream, topped with melt-in-the-mouth oat crumble and tart bursts of shaved rhubarb, then (because this was dessert and overkill is always the way forward), drowned in a pool of creamy Vanilla Anglaise, this Rhubarb Crumble Cake is rustic and chic all at once.

Rhubarb Crumble Cake with Custard Buttercream

Josef, cake fiend (and midnight nosher) that he is, had two helpings at the dinner table and kept sighing about how it reminded him of cakes from his Austrian childhood. Martina still got a piece the next day, so maybe his appetite was bested at last!

Rhubarb Crumble Cake with Custard Buttercream and Vanilla Anglaise

Makes a deep 20cm cake that serves about 10-12 people (unless they are Austrian, then maybe 6!!!!).

Shaved Rhubarb Crumble

ingredients

40g flour
40g rolled oats
40g brown sugar
50b salted butter
1 stalk rhubarb, trimmed and preferably frozen solid

mixing

Combine all ingredients except for the rhubarb in a medium bowl and rub the dry ingredients into the butter until coarse crumbs are formed. With a sharp knife, cut 1mm shavings from the stick of frozen rhubarb, and toss through the crumble mixture.

Rhubarb Crumble Cake with Custard Buttercream

Rhubarb Crumble Cake

ingredients

250g unsalted butter, softened
150g caster sugar
4 eggs
½ tsp vanilla essence
350g flour
2 tsp baking powder ½ tsp baking soda
100g ground almonds
1 tsp ground ginger
½ cup milk
600g (about 7 stalks) rhubarb, trimmed and cut into 5mm pieces

Shaved Rhubarb Crumble, recipe above

mixing

Line the base and sides of 2 x 20 cm round cake pans with baking paper.

Beat the butter and sugar until light and fluffy. Beat in the eggs, one at a time, followed by the vanilla. Add the dry ingredients and milk and beat for about 2 minutes until smooth and creamy. Stir in the chopped rhubarb until well distributed.

Spoon half the cake mixture into each pan, and smooth the surfaces.

Scatter the Shaved Rhubarb Crumble over the surface of one of the cakes.

Rhubarb Crumble Cake with Custard Buttercream

Bake the cakes at 175 degrees Celsius as follows: 40 minutes for the non-crumbled cake; 50 minutes for the crumble-topped cake. (You can bake them together on the same rack in the oven (if your oven is big enough!), just remove the first cake and let the other spend 10 minutes longer in the oven).

Cool the cakes in the pan for about 15 minutes then tip onto a wire rack to cool completely (with the crumble topped cake, you will have to gently invert it from the cake pan onto a plate then re-invert so it sits right side up on the wire rack!). Remember to peel the paper lining off the cake before assembly!

When the cakes are completely cold, sandwich them together with the Custard Buttercream, and smooth any buttercream bulges around the sides. Dust with icing sugar to serve, and pass a jug of Vanilla Anglaise around to pour over each slice of the cake!

Rhubarb Crumble Cake with Custard Buttercream

Custard Buttercream

ingredients

200g salted butter, softened
200g icing sugar
2 tbsp custard powder
65ml liquid cream (35-40% milk-fat), at room temperature (if it is straight out of the refrigerator, the buttercream will become stiff and difficult to work with)

mixing

Beat the butter, icing sugar and custard powder together until pale and creamy. Beat in the cream, about a tablespoon at a time, until it is all incorporated. Beat another minute.

Rhubarb Crumble Cake with Custard Buttercream

Vanilla Anglaise (English Custard Sauce)

ingredients

375 mL milk
1 vanilla pod (split in half), ¼ tsp vanilla powder or ½ tsp vanilla essence
3 egg yolks
60g caster sugar
1 tsp cornflour
¼ cup liquid cream

mixing

Heat the milk and vanilla pod, vanilla powder or vanilla essence until nearly boiling. If using the vanilla pod, remove, scrape out the seeds with a sharp knife, and return the seeds to the milk.

While the milk is heating, combine the egg yolks, caster sugar and cornflour in a medium bowl and whisk until the mixture starts to turn pale and foamy. When the milk has come up to temperature, pour into the egg yolk mixture in a thin stream, whisking all the time (the constant whisking stops the milk from “cooking” any one part of the egg yolk mixture more than any other part. Continue until the milk is all incorporated.

Transfer the custard to a clean saucepan and return to a low heat. Stir the custard constantly with a spatula while cooking, taking care to move the custard off the bottom of the pan to prevent sticking, and making sure that the mixture does not boil. If you are worried that the custard is getting too hot, take the saucepan off the heat for a bit from time to time, but continue to stir. The custard will gradually thicken until it makes a nice coating (about 1-2mm deep) on the back of your spatula (this takes about 5-10 minutes). If you have accidentally let your custard get too hot and boil, it will probably curdle and form a slightly grainy looking mixture. If this happens, whip out the hand beaters and beat the mixture on high for a minute or so until the mixture looks smoother.

Let the custard cool slightly once it has thickened, then pass through a fine sieve into a cold bowl (ok not to bother if you are lazy but if you curdled the custard its best to do this step!), cover with cling wrap and cool in the refrigerator. Stir the cream into the cold custard.

Vanilla Anglaise can be gently heated for serving if desired, or left cold.

Rhubarb Crumble Cake with Custard Buttercream

Enjoy!xxx