I got my hands on some beautiful forced rhubarb recently, so named because they were forced to grow in winter by exposure to frost. The stalks were a vibrant shade of pink, because they are kept in the dark, preventing any photosynthesis, and then harvested by candlelight. I’m not sure if it’s just me but rhubarb right after they’re cooked tend to taste really tangy and make my lips pucker. Leave it for a day and it mellows out. I’ve never thought to put custard (basically pastry cream) in a cake until I came across Nicola Lamb’s recipe and I’m a total convert – it’s the perfect foil to the tangy rhubarb and using vanilla bean seeds make the custard really fragrant.
There are 4 components to the recipe, so it does take a while to put together, but pretty much all the components except the cake base can be made ahead if you don’t want to spend a couple of hours in the kitchen:
- Sour cream cake base – this was moist and had a great crumb
- Custard, flecked with vanilla bean seeds – simple ingredients but involves scalding eggs with some hot milk and then cooking it over the stove again, so I’d suggest reading the recipe through a few times. Also the custard is blobbed by the tablespoon rather than spread evenly across, which actually helps the cake cook more evenly
- Rhubarb, gently roasted with sugar, orange zest and spices – I had some left over and it’s great as a topping for oatmeal / porridge too (or to top the cake)
- Buttery oat crumble topping – Nicola’s version only had butter, flour & sugar, but I’ve tweaked it to include oats. Like the custard, it’s best not to blanket the cake with the crumble so it doesn’t overbake. Plus, it’s pretty to let the rhubarb peek through!
If you don’t like / don’t have access to rhubarb, I think this cake would work great with other fruits like plums or nectarines (which could probably go on raw & bake with the cake).
Note: You can watch a video of the recipe on Instagram here.
Rhubarb & custard crumb cake
- There are multiple steps to the recipe and you can make the crumble topping, poached rhubarb & pastry cream the day before (note: allowing the rhubarb to cool will help keep the vibrant shade of pink when it’s baked). Keep them covered overnight in the fridge until ready to use.
- Leftover cake can be stored in an air-tight container at room temperature for up to 3 days.
- Cake recipe adapted from Nicola Lamb’s Kitchen Projects, Topping recipe adapted from Bob’s Red Mill
Ingredients
Poached rhubarb:
- 200g forced rhubarb, chopped into 2 inch (5cm) batons
- 20g (2 tablespoons) granulated sugar
- 20ml (1½ tablespoons) orange juice
- Zest from ½ an orange
- 1 star anise
- Grated ginger from 1 inch fresh ginger / ½ teaspoon ground ginger
Custard:
- 250g (1 cup + 1½ tablespoons) whole milk
- Seeds from ½ vanilla bean / 1 teaspoon vanilla extract
- 3 egg yolks
- 60g (⅓ cup) granulated sugar
- ¼ teaspoon fine sea salt
- 20g (2½ tablespoons) cornflour
Crumb topping:
- 90g (¾ cup) all purpose flour
- 65g (¾ cup) old-fashioned rolled oats (not instant)
- 75g (¼ cup + 2 tablespoons) granulated sugar
- ¼ teaspoon fine sea salt
- 1 tablespoon ground cinnamon
- ¼ teaspoon freshly grated nutmeg, optional
- 100g (7 tablespoons) unsalted butter, melted
Cake:
- 120g (½ cup + 1 teaspoon / 1 stick + 1 teaspoon) unsalted butter, softened
- 50g (¼ cup) granulated sugar
- 50g (¼ cup) light brown sugar
- 2 medium eggs, room temperature
- 155g (1 cup + ⅓ cup) all-purpose flour
- ½ teaspoon baking soda
- ½ teaspoon baking powder
- ¼ teaspoon fine sea salt
- 120g (½ cup) sour cream
- 1 teaspoon vanilla extract
Directions
Poached rhubarb:
- Preheat oven to 170°C (340°F). Toss chopped rhubarb with granulated sugar, orange juice, orange zest, star anise and grated / ground ginger.
- Transfer to a roasting tin and bake in oven for 12 – 15 minutes, until the rhubarb stalks can be pierced with fork, but hasn’t completely disintegrated yet.
- Leave aside to cool. Refrigerate if you’re making this the day before baking the cake.
Custard:
- To make the custard, heat milk and scraped seeds from vanilla bean / vanilla extract in a saucepan over medium heat until simmering.
- In a medium bowl, whisk egg yolks with cornflour, sugar and salt until mix has lightened in colour and sugar has dissolved.
- Once milk is bubbling, pour half of the hot milk over the yolks to temper. Return the whole mixture to the saucepan.
- Cook the mixture in the saucepan, whisking all the time, until the mixture is thick and bubbling (roughly 3 minutes). Pour into a bowl and press a cling film on the surface of the custard to prevent a skin from forming. Set aside to cool and refrigerate if making this the day before baking the cake.
Crumb topping:
- Combine flour, oats, sugar, cinnamon, nutmeg and salt in a small bowl.
- Pour melted butter and mix until it comes together. It will be lumpy. Set aside.
Cake:
- Cream softened butter, granulated sugar and light brown sugar together with an electric hand mixer for 2-3 mins until light (it will take slightly longer if you’re mixing with a spatula).
- Add the eggs in one at a time, mixing the first one well before adding the second (the mixture might look curdled but it will come together in a bit).
- Sift in flour, baking soda, baking powder and salt. Mix until just combined.
- Stir through the sour cream and vanilla extract until everything is mixed well.
Assembly:
- Preheat oven to 170°C (340°F).
- Line an 8 inch (20cm) square pan with parchment paper, leaving enough overhang to catch the crumbs.
- Pour the sour cream cake batter into the pan and smooth the surface.
- Using a tablespoon, blob the custard across the surface. Spoon the rhubarb sticks evenly over the top, then sprinkle the oat crumb topping generously (making sure that there is still space for rhubarb and custard to peek through to allow for even baking).
- Bake for 45 – 50min, until a toothpick inserted in the centre comes out clean without cake bits (there might be custard bits).
- Leave to cool for at least 1 hour before slicing into squares. Enjoy with leftover poached rhubarb or on its own!
earl grey thursday 