This traybake instantly took me back to those carefree village fêtes of childhood—plastic tablecloths, lemon barley water, and queues snaking around tables as you hoped your favourite slice hadn’t vanished.
The first time I made it? Disaster. I let the margarine get too soft and rushed the mixing. The result: a sunken, dense sponge that tasted okay… but missed that Mary Berry magic.
Second try, I followed her instructions exactly—cold margarine, all-in-one method, a full five-minute mix—and it was a revelation. Fluffy golden sponge, crisp white icing, joyful sprinkles. Like a party in a pan.
Let me walk you through how to make it perfectly. No sinking, no stress.
Why This Recipe Just Works
This is Mary Berry at her best: the all-in-one method keeps it simple, fast, and consistent. Using chilled margarine might sound strange, but it helps create a light, airy batter that holds its shape beautifully in the oven.
And the icing? Boiling water transforms powdered sugar into a glossy glaze that sets firm—no butter, no cream cheese, just that satisfying sweet crackle on top.
Best part? It stays good for days. Most traybakes go soggy or sticky—this one keeps its bounce and bite.
Ingredients & Why They Matter
For the cake:
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225g Chilled Block Margarine – Straight from the fridge. Skip the soft spreads—they’ll make it dense.
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225g Caster (Superfine) Sugar – Dissolves easily for a fine, even crumb.
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275g Self-Raising Flour – For a consistent rise without extra effort.
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1 tsp Baking Powder – Boosts the lift, even with self-raising flour.
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4 Large Eggs (Room Temp) – Trap air better and mix more evenly.
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4 tbsp Milk – Loosens the batter just enough to spread well.
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1 tsp Vanilla Extract – Adds warmth and balances the sweetness.
For the icing:
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300g Icing (Confectioners’) Sugar
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3 tbsp Boiling Water
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2 tbsp Coloured Sprinkles – Optional… but why wouldn’t you?
Make It Your Own (Without Breaking It)
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Prefer Butter? Go ahead—but expect a denser texture.
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Gluten-Free? Works great with Doves Farm GF self-raising flour—just add 1 tbsp extra milk.
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No Sprinkles? Try flaked almonds or freeze-dried raspberries for a classy upgrade.
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Lemon Twist? Swap the vanilla for zest + juice of 1 lemon. Refreshing!
Mistakes I’ve Made (So You Don’t Have To)
| What Went Wrong | Why It Happens | How to Fix It |
|---|---|---|
| Cake too dense | Margarine too soft | Use cold, block margarine |
| Icing melted off | Cake was still warm | Cool completely before icing |
| Cake cracked on top | Oven too hot or batter too stiff | Use correct temp + don’t skip the milk |
| Icing too runny | Too much water added | Start with 2 tbsp, add slowly |
Step-by-Step: Mary Berry’s Confetti Traybake
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Preheat your oven to 180°C (160°C fan) / 350°F. Grease and line a 12×9-inch (30×23cm) traybake tin.
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Mix the batter: Add margarine, sugar, flour, baking powder, eggs, milk, and vanilla to a large bowl. Beat with an electric mixer for 3–5 minutes until smooth and pale.
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Bake: Pour into the tin, smooth the top, and bake for 30–35 minutes until golden and springy.
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Cool: Leave in the tin until fully cool. (Trust me, don’t rush it.)
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Ice it: Stir icing sugar and boiling water until smooth. Spread over the cake.
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Decorate: Scatter sprinkles while the icing is still wet. Let it set, then cut into 20 squares.
Pro Tips From My Kitchen
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Beat the batter for the full 5 minutes—you’ll see the difference.
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Use the back of a warm spoon to smooth icing—it glides better.
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Freeze your sprinkles! Helps keep their colour sharp on warm icing.
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If the corners brown too quickly, tent with foil for the last 5 minutes.
Storage & Serving
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Room Temp: Airtight container, up to 5 days.
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Freezer: Freeze squares with parchment between layers. Defrosts in under an hour.
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Serve with: A strong mug of tea. Or level it up with whipped cream or a scoop of vanilla ice cream.
FAQs
Q: Can I use butter instead of margarine?
A: Yes—but expect a richer, denser cake. For fluffiness, margarine wins.
Q: My icing’s runny—help!
A: Add a bit more icing sugar. It should be spreadable, not pourable.
Q: Can I halve the recipe?
A: Absolutely. Use an 8-inch square tin and start checking after 25 minutes.
Q: Why did my cake sink?
A: Most likely underbaking or not beating long enough. Use the skewer test!
Q: Can I make it ahead?
A: Definitely—it gets better overnight. Store airtight and add sprinkles just before serving if you want them extra crisp.
