120gunsalted buttercut into dice (needs to be very cold)
For the cardamom custard
1 ½tbspcaster sugar
Preheat the oven to 180C/gas 4.
Begin by making the crumble topping, as this needs some time to rest in the freezer or fridge while you prepare the rhubarb. Add the flour and diced butter to a food processor and pulse until combined. If you don’t have a food processor, the ingredients can be mixed (literally crumbled) by hand in a large bowl.
Once the butter and flour has an ideal crumble texture, gently incorporate the porridge and almond by pulsing just once or twice to avoid grounding the almonds or oats.
Put the crumble topping into a zip lock bag or bowl and chill in the freezer for 10 minutes, or in the fridge for at least 20 minutes.
Wash the rhubarb, remove the ends and slice each stick into approx. 2cm-1 inch pieces.
Add the rhubarb to a suitable baking dish for the crumble. Top with the granulated sugar, ginger, vanilla, cinnamon, a pinch of salt, the lemon juice, and a tablespoon of water. Mix and place in the oven for 15 minutes, stirring once while cooking.
As rhubarb gives off a lot of moisture, you may want to drain some of the liquid at the point, to prevent the crumble topping from getting soaked. Reserve it to use later.
Pour your cold crumble topping over the rhubarb, making sure it’s all covered, but try to keep the topping fairly loose.
Place the crumble tray in the oven for around 30-45 minutes, using a baking tray as an extra support to collect any juices that escape.
Once golden, remove from the oven, rest for five minutes and serve with custard (or cream, if you really must). Optionally drizzle some of the excess rhubarb juice from cooking over the crumble.
To make the cardamom custard
While the crumble is baking, prepare the custard by removing the cardamom seeds from their pods and lightly crushing with a pestle and mortar, or the back of a spoon. Add to a small saucepan with the cream and vanilla extract, and heat until steaming but not boiling.
Remove from the heat and cover the pan, allowing the cardamom to infuse for 20 minutes.
Whisk the egg yolks with the sugar. Once incorporated, add the flour and mix well. Pour some of the cardamom cream into the eggs (approx. one ladle) and whisk to combine. Slowly add the rest of the liquid to the bowl and whisk until completely incorporated.
Strain the liquid back into the pan and cook over low heat, whisking almost constantly, until the custard is thick. It’s absolutely crucial to cook over a low heat without rushing this stage to avoid scrambling the egg yolks. If the custard does become clumpy, it may be salvageable by instantly removing from the heat and whisking an ice cube or two into the pan.
Once prepared, serve as quickly as possible to prevent a thick skin from forming.