Rhubarb and custard cake

Method

• step 1

  First, make the custard. Put the custard powder and sugar in a small pan and whisk to combine. Pour in the milk and whisk until smooth. Put the pan over a medium heat and warm, whisking constantly, until the custard thickens and just starts to bubble. Add in the butter and mix until melted and combined. Scrape the custard into a small bowl, press a sheet of baking paper on the surface, and chill until cold.

• step 2

  To make the crumble, mix together the flour, sugar and a pinch of salt in a small bowl. Rub the butter into the flour mixture using your fingertips until a dough forms. Cover and chill until firm.

• step 3

  Meanwhile, to make the cake, lightly butter a loose-bottomed, deep, 23cm round cake tin (a springform tin will also work well) and line the base with baking paper. Heat the oven to 180C/fan 160C/gas 4.

• step 4

  Put the butter and sugar in a large bowl and beat using an electric whisk for 5 minutes until light and fluffy. Add the eggs, one at a time, beating until combined before adding another. Add the vanilla and beat again to combine. In a separate bowl, whisk together the flour, baking powder and ½ tsp of fine sea salt. Add the flour mixture to the wet ingredients in three additions, alternating with the soured cream. Make sure to start and finish with the flour mixture.

• step 5

  Scrape the batter into the prepared cake tin and level the surface. Remove the crumble and custard from the fridge. Dollop the custard over the cake batter, then scatter over the rhubarb pieces. Break up the crumble and arrange it over the rhubarb. Bake for 50 minutes or until golden and the cake is just pulling away from the sides of the tin. Leave to cool for 15 minutes before removing to a wire rack to cool completely. It will keep, covered, at room temperature for three days.