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School Cake recipe by Baking with Granny. Sponge cake with white icing and rainbow sprinkles.

School Cake

The original School Cake - a simple sponge cake, topped with a thick layer of white icing and a generous amount of rainbow sprinkles. Best served with custard (pink or otherwise!).
4.98 from 69 votes
Print Recipe
Course: Dessert
Cuisine: British, Scottish
Prep Time: 20 minutes
Cook Time: 40 minutes
Total Time: 1 hour
Servings: 12

INGREDIENTS
 

INSTRUCTIONS

  • Pre-heat your oven to 180°c (160°c for fan-assisted ovens, Gas Mark 4 or 350°F) and a 9x12 inch baking tin with greaseproof paper. Set aside.
  • In a large bowl, cream together the margarine and sugar until light and fluffy.
  • Add the eggs one at a time, ensuring each is mixed through before adding the next.
  • Sift in the flour and gently fold to create a batter.
  • Transfer the batter to your pre-lined tin and bake in your pre-heated oven for 30-40 minutes until risen, golden, and a skewer inserted comes out clean.
  • Leave to cool in the tin for a few minutes before transferring to a wire rack to cool completely.
  • Once your cake has cooled completely, mix the icing sugar with a few teaspoons of boiling water in a bowl, adding a little water at a time until you have a thick pouring consistency. Pour the icing onto your cake, using a spoon to guide it to the edges. Finish with some rainbow sprinkles.

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IMPORTANT NOTE:

All my recipes are developed using a digital scale and the metric system (grams and millilitres). Cup measurements are available as a conversion but these, unfortunately, won't always be as accurate. For best results, I always recommend baking with a digital scale.

NOTES

Egg Size:

When it comes to eggs, I always buy the Mixed-weight Free-range Eggs. Generally speaking, egg size doesn’t make a huge difference in most baking, unless you are using sizes that lean into the extremes. But with that in mind, medium-sized eggs are probably the best option if you are unsure what size eggs to use.

Substitutions:

  • Margarine: I use a soft baking margarine in most of my sponge cakes because I find it to be easier & more predictable to use, while always giving a light, moist crumb to your cake. You can swap this out for butter if you prefer, but make sure you use a very soft butter for the best results.
  • Caster Sugar: When it comes to sponge cakes, caster sugar is preferable as the finer consistency is ideal for mixing through the batter. In a pinch, you could swap it for granulated sugar. In terms of taste, it would be fine, but the texture of your sponge may vary slightly because less-fine sugars won't dissolve into the batter as efficiently.
  • Self-raising Flour: Although easy to buy in the UK, self-raising flour isn't always available across the world, but you can easily create your own. For this recipe, you would use 280g of Plain Flour and 3.5 tsp of Baking Powder (baking soda). I always recommend both mixing and sifting the flour & baking powder together before using to make sure they are very well combined.

Storage:

Store your old School Cake in an airtight container at room temperature. It’ll keep well for up to 4-5 days, if it lasts that long!

Freezing:

You can freeze the sponge, but this is best done before adding the icing and sprinkles. Wrap the cake tightly in cling film and foil, and freeze for up to 3 months. Defrost at room temperature, then finish with the icing and sprinkle before serving.

Serving:

For full school-dinner nostalgia, serve with a drizzle of custard (pink or otherwise!).

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