This gluten free Rhubarb and Custard Cake recipe is inspired by the favourite childhood rhubarb and custard sweets and turns them into delicious cake… Pistachio sponge layered with creamy sweet custard and tangy rhubarb compote. If preferred use a plain vanilla sponge. (Optional dairy free)
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Gluten Free Rhubarb and Custard Cake – A childhood treat revamped
My gluten free Rhubarb and Custard Cake is delicious. Made with a moist Pistachio Sponge, the cake itself is rich, soft and nutty-sweet… Layering perfectly with creamy sweet custard and tart, tangy rhubarb compote. The rhubarb and custard combo is a British classic. Like cheese and onion or gin and tonic, they are made for each other. It’s one of my favourite flavour pairings.
Like so many children though, I hated rhubarb when I was little. The sharpness and slight ‘squeek’ on the teeth was too much for my young palate. But my dislike of rhubarb strangely didn’t extend to the now ‘retro’ rhubarb and custard boiled sweets. Their half yellow, half pink sugar-coated sweet and sour crunch tempting me on visits to the sweet shop.
The classic and indeed iconic marriage of sharp against creamy sweetness is joyfully replicated in this cake… Heavenly nostalgia for the tastebuds.
Gluten Free Pistachio Cake for an extra treat…
The original plan for my Rhubarb and Custard Cake was to make it as a layer cake with gluten free vanilla sponge. But in a major larder clear-out, I found a huge stash of pistachios left over from making Pistachio Marzipan at Christmas. Since they were heading for their ‘best before’ date, it seemed only right to incorporate them into the recipe. And a Pistachio Cake offered a modern twist to accompany my pink and yellow foray into childhood.
The Pistachio Cake was an adaptation of my tried and tested Best Gluten Free Vanilla Sponge recipe… A simple tweak from using the ground almonds in the original recipe to home-ground pistachio flour. It worked a treat… The pistachios adding not only a slightly sticky moistness to the sponge, but also a subtle green hue.
What is the best custard for Rhubarb and Custard Cake?
While you could make your own Crème Pâtissière custard, it really is unnecessary for Rhubarb and Custard Cake. The iconic childhood custard sweetness is perfectly replicated using bog-standard custard powder (I used Birds brand).
But whether you make your own custard from scratch or use custard powder, be sure to make it thicker than you would for pouring. It needs to be spreadable when cold and robust enough to hold the weight of the top layer of the cake.
Making rhubarb compote for Rhubarb and Custard Cake
The compote is really simple to make too… A quick and dirty stewing of rhubarb with some sugar on the hob… Reduced to again be thick enough for spreading and layering. Having stewed down the rhubarb, I confess I did add a tiny hint of red food colour to brighten the appearance. But this is of course optional.
The best time to find locally-grown rhubarb is spring to summer. And if you have a garden (large or small), it is thoroughly worth growing a rhubarb plant. It gives and gives, so is more than worth the money, especially if you plan to make lots of rhubarb and custard (cake or otherwise).
Which is better… Small cakes or a large layer cake?
The recipe shared here for gluten free Rhubarb and Custard Cake is enough for a bit of both as much as one or the other… And either are delicious. When I made the Pistachio Cake base, I used my Mini Sandwich Cake Tin to make individual cakes… But the tin was only for 12 little cakes and I probably had mixture for nearer 18 to 24. So, I used the remaining sponge batter for a further 7 inch layer cake.
The alternative is to make a single 9 inch layer cake, or two 7 inch layer cakes… The gluten free pistachio sponge freezes really well (wrap tightly to keep it fresh in the freezer)… So, any ‘excess’ can be saved to make another layer cake later… Or be used for making delicious trifles.
If you want to use less mixture and make less sponge, that’s fine too. Simply reduce the ingredients by one or two thirds for a smaller quantity using the recipe card calculator.
Want to make Rhubarb and Custard Cake with a different gluten free sponge?
If you love the idea of making Rhubarb and Custard Cake but with a different sponge, I won’t be offended. At Gluten Free Alchemist there are lots of sponge recipes to choose from. From a ‘pairing’ perspective, the Vanilla Cake or Victoria Sponge Cake are probably the simplest options… But I think Orange Cakes with Rhubarb and Custard would be sublime. And a Rhubarb and Custard Swiss Roll would be seriously fun.
Made gluten free Rhubarb and Custard Cake?
And as always… Thanks for reading and taking the time to visit Gluten Free Alchemist.
Other favourite rhubarb recipes at Gluten Free Alchemist
- Rhubarb Frangipane Tart
- Strawberry Rhubarb Crumble Slice
- Rhubarb Upside Down Cake
- Strawberry & Rhubarb Jam
- Rhubarb Curd
- No Churn Rhubarb Ice Cream
- Rhubarb & Strawberry Meringue Pie
- White Chocolate & Rhubarb Eclairs
- Rhubarb & Strawberry Sauce
Rhubarb and Custard Cake
- mini Victoria Sandwich tins and/or baking tins of preferred size (2 x 9 inch max)
- oven + hob
- measuring jug
- 320 g plain gluten free flour blend I use GFA Blend A (see NOTES)
- 160 g ground pistachio nuts (pistachio flour) raw, shelled pistachios home-ground to a medium powder/meal
- 1 tsp xanthan gum
- 2 tsp baking powder gluten free
- 1 tsp bicarbonate of soda baking soda
- ½ tsp fine sea salt
- 330 g/ml milk dairy free if required
- 1½ tbsp white wine vinegar
- 170 g unsalted butter softened (or good dairy free alternative)
- 360 g caster sugar
- 2 tsp vanilla extract
- 3 large eggs at room temperature – lightly beaten (UK large (Canadian ‘Extra Large’; Australian ‘Jumbo’; and US ‘Extra or Very Large’)
- 3 to 4 stalks fresh rhubarb cut into small pieces
- 1-2 tbsp golden caster sugar
- drop red food colour optional – to colour as desired
- 45 g custard powder gluten free/dairy free – I use Birds
- 2 to 3 tbsp caster sugar
- 570 ml full fat milk (1 pint) or dairy free alternative
- icing sugar to dust confectioners sugar
- Base line the cake tins (large or small) with baking paper.
- Pre-heat the oven to 180 C/350 F/Gas 4.
- Weigh and mix together the flour, ground pistachios, xanthan gum, baking powder, bicarbonate of soda and salt. (TIP: weigh into an airtight container and shake vigorously). Set aside.
- Using a jug, mix together the milk and vinegar and set aside for 10 minutes (the mixture will become slightly clumpy as it turns into 'buttermilk').
- In a large bowl, cream together the butter, sugar and vanilla extract using an electric whisk, until pale and fluffy.
- Gradually add and beat in the eggs a little at a time.
- Gently fold in about a third of the milk mix followed by a third of the flour mix and repeat in thirds until all the dry mix and liquid have been just incorporated into the cake batter. Be careful not to over-mix.
- Spoon the batter into the prepared tins (about two-thirds full) and smooth the tops.
- Bake for about 15-20 minutes (small cakes) and 25 to 35 minutes (larger cakes) until the top springs back and a skewer inserted into the centre comes out clean.
- Remove from the oven and leave to cool in the tins for about 10 minutes, before turning onto a wire rack to cool completely. If the sides appear 'stuck' gently run a flat knife around the edges of the tin before turning out.
- Place the chopped rhubarb and sugar with a tablespoonful of water in a saucepan over a medium heat on the hob.
- Bring to a slow simmer, frequently stirring until the sugar dissolves and the rhubarb has softened and disintegrated.
- Continue to simmer, stirring frequently until the liquid has reduced and you have a thickened rhubarb compote. The compote needs to be thick enough to spread and hold its shape.
- Add a drop of colour if using and stir through thoroughly.
- Set aside to cool completely (stirring occasionally).
- Mix together the custard powder and sugar in a medium saucepan. Do NOT put on the heat at this stage.
- Add a couple of spoons of milk and blend together into a smooth paste.
- Gradually add the rest of the cold milk, stirring until you have a smooth liquid.
- Over a low heat, very gradually bring the custard to a simmer, stirring continually to prevent any lumps forming.
- As the custard approaches simmer point it will begin to thicken and at this stage, it will be important to stir vigorously to ensure it remains smooth.
- Once the custard has begun to very gently bubble, remove from the heat and pour into a bowl.
- Place a piece of clingfilm over the bowl in contact with the surface of the custard to prevent a skin forming as it cools.
- Once the custard is cold, whip with a whisk to lighten slightly.
Putting it all together
- When ready, cut small individual cakes in half or use the larger sponges as individual layers.
- Spread a thick layer of rhubarb compote on the base layer and a thick layer of custard on the underside of the top layer and gently sandwich together.
- Sprinkle the top with icing sugar.
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