400g rhubarb, trimmed and cut into 2cm lengths
225g caster sugar
250g slightly salted butter, softened, plus extra for greasing
3 medium eggs
175g self-raising flour (we used Dove's Farm gluten free)
50g custard powder (we used Bird's)
100g ground almonds
500g tub Waitrose Seriously Creamy Madagascan Vanilla Custard
12 sugar cubes, crushed (we used Pearlsugar)
Preheating the oven to 220C, we prepared the rhubarb by placing it on a non-stick baking sheet, sprinkling with 25g of the caster sugar and baking for about 15 minutes until it began to soften.
Reducing the oven temperature to 170C (fan) we then began making the base of the traybake.
The remaining 200g of the caster sugar, softened butter, eggs, flour, custard powder, ground almonds and 100g of the custard were mixed together (we used an electric hand mixer). This produced quite a firm mix and we brought it together, scraping around the bowl, using a silicone spatula.
Having prepared a shallow, non-stick 23cmx33cm baking tray by greasing it (we used the wrapper from the butter) and lining with baking parchment, we were ready to add the 'base' of the traybake.
Spreading the base mix out as evenly as possible, a dessertspoon was used to press into the mix and make 'wells'...
... which were then filled with the remaining ready-made custard.
Spreading the cooked (and cooled) rhubarb over the base, the traybake was ready to be baked.
We checked the traybake after 30 minutes at 170C and left it in the oven for a further 15 minutes - until the sponge was firm and the custard still had a bit of a wobble.
Taking the traybake out of the oven, it was placed on a wire rack and left to cool in its tin.... we sprinkled over a tablespoonful of pearlsugar (Scandinavian sugar).
The cooling traybake looked impressively like the one in the recipe we were following.
Once the traybake was fully cooled, we cut it into 15 pieces and were pleased that it stayed together nicely. The sponge base was lovely and soft but kept its shape. Finding the pockets of custard, now firm and unctuous, with the tart rhubarb topping gave each portion a lovely range of tastes and textures.