From Adam Ragusea.

Thanks to Helix Sleep for sponsoring! Visit https://helixsleep.com/ragusea to take advantage of their Black Friday Exclusive Partner Offer and get 27% off site-wide!

***RECIPE***

For the cake

200g (14 tablespoons) butter
200g granulated sugar
3 eggs
200g (1 2/3 cups) all-purpose flour
2 teaspoons baking powder
1-2 teaspoons vanilla
pinch of salt, if using unsalted butter

For the custard

2 egg yolks
50g (1/4 cup) granulated sugar
1 teaspoon cornstarch or flour
150mL milk
150mL cream
1/2 teaspoon vanilla
tiny pinch of salt

For the icing

250g (2 1/2 cups) powdered sugar
2-3 tablespoons water
Rainbow sprinkles

Soften the butter for the cake by leaving it on the counter for a few hours or microwaving it for a few seconds. Whip it with the sugar for a few minutes until fluffy. Beat in the eggs one by one. Beat in the vanilla, baking powder, flour and a pinch of salt if you’re using unsalted butter.

The batter should be stiff, like cookie dough. Scrape it into a square brownie or cake pan (9×9 inch or 8×8, standard sizes) that you’ve greased and/or lined with parchment paper. Try to spread the batter out to the edges in a reasonably even layer. Bake at 350ºF/180ºC, but adjust temp down if using a convection fan, per your oven’s instructions.

Be careful not to over-bake the cake as it will tend to be dry — take it out when it just barely passes the toothpick test. Mine took half an hour. Get it out of the pan and let it cool all the way before icing.

For the custard, put the egg yolks into a cold saucepan with the sugar, starch, vanilla, and salt, and whisk in just enough of the dairy to make a thick paste. Whisk until smooth, then whisk in the rest of the dairy. Bring to a simmer while whisking frequently, until it thickens. Chill before serving — if it’s too thick by the time it cools, thin it out with more milk or cream.

For the icing, whisk just enough water into the powdered sugar to render it a fluid — if it’s too thin, you’ll get a glaze, not an icing. When the cake is cool, pour the icing on top and gently spread it to the edges. Immediately top with rainbow sprinkles while it’s still wet and sticky. Let the icing set for at least an hour before slicing.

Serve slices with custard.

This recipe is adapted from Prue Leith’s recipe on the Great British Bake Off: https://thegreatbritishbakeoff.co.uk/recipes/all/prue-leiths-school-cake-and-custard/