Gluten-Free Chocolate School Cake

I bake my Vanilla School Cake for all our family parties and this year I couldn’t resist adding a chocolate version to the menu which has been such a success that it’s fast achieved legendary status amongst our friends and family.

These large sheet cakes are perfect for serving to a crowd. It’s essential that they are the easiest cakes I bake as there are always so many jobs to do when it’s party time that you need the cake to be simple and foolproof. And you need them to have mass appeal.

There isn’t any melted chocolate in either the sponge or the icing and this is deliberate to both keep the cost down and to make the cake faster – no hanging around the stove waiting for the chocolate to melt. Plus easier washing up. And actually you do not miss it at all. I was worried that the cake would be drier. Not so. It’s still so incredibly moist and rich in intense chocolate flavour. And the Chocolate Glaze Icing is even fudgier than a regular ganache and such a revelation. I now use it to glaze all my chocolate treats.

We’ll walk through the very simple steps so you can make your Chocolate School Cake from the easy storecupboard ingredients, how to store this cake, how to make a quick glaze and how many people this cake can serve. Plus lots of variations on toppings!

And if you have time or if you are serving this cake for dessert then you’ll be in heaven serving it with this Homemade Chocolate Custard. When it’s warm it slightly melts the fudgy icing making chocolate pudding perfection.

Watch the Video

Sometimes it helps to see a visual of what I'm talking about. So watch the video to see what it looks like to make your Chocolate School Cake.

What’s a School Cake?

These kind of cakes are comfort eating at its best; reminiscent of the kind of large traybakes that were traditionally served in school lunch halls (particularly in the 80s and 90s as I don’t think my children have them as much). They have mass appeal and were usually decorate in a simple icing and plenty of sprinkles. Always served with ladleful’s of thick custard.

This recipe is very different to my regular Gluten-Free Chocolate Traybake as it’s baked in a larger tin to specifically serve a bigger crowd with cheaper ingredients (no melted chocolate). It’s a lighter, soft and fluffy sponge and is topped with a thin layer of no-fuss chocolate sugar icing and sprinkles. There’s no fancy buttercream, ganache or piping work. It’s the quickest and easiest chocolate cake I have on my website.

If you love this recipe then check out my original Vanilla School Cake which is served with strawberry (pink!) custard.

Ingredients Needed

For the sponge cake

Gluten-Free Flour – FTL Blend. This recipe uses my Homemade Gluten-Free All Purpose Flour which works really well here as the flour ratio has been carefully tested to ensure the mix between wholegrain flours and starchy flours is balanced. This also means we don’t need to use xanthan gum as the blend is strong enough and produces a well structured and textured bake which can hold together without needing any extra binders.

This flour blend is a mix of 4 different flours: sweet rice flour (glutinous rice flour), sorghum flour, oat flour, tapioca flour (tapioca starch).

There are plenty of flour substitution tips ideas if you click on the original post for this homemade flour mix.

Eggs. This recipe uses medium size, about 60g each with shell (50g each without shell). These are often classified as large eggs in the US. I recommend weighing your eggs to ensure the correct amount.

Light brown sugar. Gives lovely gentle molasses flavour and moisture.

Olive oil. This is my preferred oil in cakes. To avoid a strong flavour use a flavourless mild and light olive oil. You can use vegetable oil or coconut oil.

Milk. Use whole milk or your favourite plant based milk if you are making dairy-free (I like oat milk or almond milk).

Vanilla extract. You don’t need to use the best quality vanilla extract here as there's already a lot going on with the flavours and it won't make a difference. A supermarket brand is just fine.

Cocoa powder. Choose a high quality organic brand if possible. This recipe was tested with Dutch-processed cocoa powder (which is the more common type in the UK – but do check the labels) which means it has been treated with an alkalising agent to neutralise its acidity, resulting in a smoother, milder flavour and allowing for a better rise in tandem with the baking powder.

Baking powder. A leavening agent which causes the cake to rise and become light and fluffy. Do check your baking powder is gluten-free before use.

Salt. I like to use kosher salt in my baking as it has a round gentle flavour. Using salt in your baked goods lifts and sharpens all the other flavours.

For the Chocolate Glaze Icing

Icing sugar. (powdered sugar). Icing sugar dissolves easily into the milk, resulting in a smooth texture, whilst giving perfect sweetness.

Cocoa powder. As above this recipe uses Dutch-processed cocoa powder (which is the more common type in the UK – but do check the labels).

Milk. You can use whole milk or dairy-free milk if you need it to be.

Golden syrup. Use this in tandem with the icing sugar as it gives smoothness and a gorgeous gloss to the icing.

Vanilla extract. Since the main flavour is the chocolate in this glaze you can get away with using a lower quality vanilla extract. A regular supermarket brand will do just fine.

Salt. A little kick of salt in the icing really elevates the flavour and balances out the sweetness.

How To Make Gluten-Free Chocolate School Cake

For full recipe instructions go to the recipe card at the end of this post.

In another bowl, sift and whisk together the flour, cocoa powder, baking powder and salt.

In a large bowl, or jug, whisk together the eggs, sugar, olive oil, milk and vanilla until smooth.

Pour the wet ingredients into the dry ingredients and mix until just combined.

Pour the batter into a prepared large rectangular baking tin, spread evenly and bake for 40-45 minutes, until a skewer inserted in the centre comes out clean.

How To Make The Chocolate Glaze

Sift the icing sugar, cocoa powder and salt in a large bowl.

Warm the milk, vanilla and golden syrup in a small saucepan until the syrup has dissolved. Gradually pour the warm milk mixture into the dry ingredients.

Whisk together until smooth and just pourable. Add a little extra milk if needed. Pour the glaze evenly over the cooled cake and leave to set for about 1 hour.

If decorating with sprinkles, wait until the glaze has thickened slightly so they don’t sink.

Make Ahead

You can make the chocolate sponge up to 2 days before glazing and serving. Store the sponge cake in an airtight container and keep in a cool dark place. Or freeze using the instructions below.

I recommend this large rectangular cake box to store the cake.

The whole cake can be made, including the glaze, up to 2 days before serving. Store in an airtight container and keep in a cool dark place

Freezing

Whole Cake. You can freeze the sponge cake successfully for up to 3 months. I recommend freezing without the glaze. First wrap the cooled whole cake tightly in cling film (plastic wrap) and then double wrap in aluminium foil. Don’t forget to label including the date. To enjoy, thaw at room temperature overnight, unwrap once thawed and decorate with the glaze.

Individual Slices. You can also freeze the cake glazed in squares. It needs a little more care when freezing:

• Place the school cake squares on a tray and flash freeze the cake squares for 6-8 hours, before wrapping each slice up individually in cling film (plastic wrap) and placing in an airtight container.
• To thaw, remove the cake squares individually, unwrap whilst frozen so not to disturb the glaze. They should take about 2 hour to fully thaw, depending on the size.

Recipe Variations

This Chocolate School Cake is a great base for so many different chocolate cakes. You can change the flavour or make it more sophisticated. It’s time to get creative.

Alternative Flavours

Chocolate Orange School Cake. Use finely grated zest of 1-2 unwaxed oranges to the sponge ingredients before baking. ½ teaspoon orange extract is better for the chocolate glaze. You can decorate with caramelised oranges.

Chocolate Mint School Cake. Use ½ teaspoon – 1 teaspoon peppermint extract to the sponge (taste for desired flavour as different extracts have different strengths). Use ¼- ½ teaspoon peppermint extract in the glaze.

Mocha School Cake. Add 2 teaspoons instant espresso powder to the dry ingredients in the sponge. For the glaze add 1 teaspoon espresso powder to the milk as you are warming the ingredients.

Alternative Glazes

Swap the Chocolate Glaze Icing for Chocolate Fudge Buttercream or and easy Chocolate Ganache or even a Cream Cheese Buttercream (then drizzle over a small amount of the chocolate glaze icing).

If you are serving with the chocolate custard you can even choose skip the glaze and just dust with a little icing sugar.

Alternative Toppings

Here we have gone traditional and decorated our school cake with sprinkles. However, you can swap the sprinkles for any of the following:

Chocolate curls. Use a grater to slide down the side of a bar of dark chocolate to create fresh chocolate curls – delicious on the top of this cake.

Fresh berries. Raspberries are my favourite to decorate this cake, but you could accompany with strawberries, blueberries or anything in season.

Serving Suggestions

Have I mentioned the luxurious Chocolate Custard that I developed especially to go with this recipe? It’s worth the little extra step.

If that doesn’t tempt you then why not try a Fresh Strawberry (pink!) Custard to accompany. Of if you are more sedate then Vanilla Custard is also a delicious choice.

I would also be remiss not to mention my favourite dessert in the whole world which is a warmed slice of this cake topped with the best Homemade Vanilla Ice Cream. Gah!! I love it so much!

More Gluten-Free Chocolate Cakes You’ll Love

This Chocolate Raspberry Cake features a gorgeous buttermilk chocolate cake, sandwiched with a simple fresh raspberry swiss meringue buttercream.

This incredible Chocolate Cake is rich with chocolate and will become your new go-to gluten-free special occasion cake. It boasts moist and tender cake layers filled with a luxuriously silky chocolate buttercream frosting for the ultimate indulgence.

Espresso Chocolate Cake with Salted Caramel Buttercream is a chocolate lover’s dream with espresso spiked chocolate sponge layers sandwiched together with silky salted caramel swiss meringue buttercream and drizzled with thick luscious homemade salted caramel.