Mary Berry Chocolate Mirror Cake

The first time I made this cake, I had no business attempting anything so glossy. I’d just watched one too many baking shows and thought, “How hard can it be?” Famous last words. My first glaze split, my sponge collapsed a bit in the middle, and the kitchen looked like a chocolate scene from a horror film.

But here’s the thing—I couldn’t stop thinking about that mirror finish. So I tried again. And again. And by the third round, I cracked it: the right temperature, the right texture, and most importantly, the right patience. Let me show you how I got it to shine like a chocolate lake at sunset.

WHAT MAKES THIS RECIPE SPECIAL

This cake is a visual stunner, yes—but it’s also smartly built:

• Light sponge base – Soaks up the glaze beautifully without sinking.
• Proper mirror glaze – That real high-shine finish? It comes from gelatin + chocolate + timing.
• Not just a pretty face – The glaze isn’t just for looks. It adds a rich, almost ganache-like contrast to the sponge.

And what surprised me most? It stays shiny in the fridge. I thought the fridge would kill the gloss—but nope. Mary comes through again.

INGREDIENTS + WHY THEY MATTER

FOR THE CAKE

• Eggs (4 extra-large) – These are the structure. You want them whipped to ribbon stage for that airy lift.
• Sugar (125g) – Helps aerate and sweeten. Granulated works fine, but caster is a touch smoother.
• All-Purpose Flour (125g) – Keeps it light. Sift it, always.
• Baking Powder (1½ tsp) – Gives it a gentle rise. Don’t overdo it or the cake domes.
• Salt (¼ tsp) – Balances the sweetness.
• Melted Butter (55g) – Adds richness without weighing it down. Fold it in last to keep the air bubbles.

FOR THE MIRROR GLAZE

• Powdered Gelatin (2 envelopes / 14g total) – The magic behind the mirror. Don’t let it boil, or it’s game over.
• Sugar (225g) – Sweetness and structure.
• Cocoa Powder (75g) – Deep chocolate flavour. Use a good one—it matters here.
• Heavy Cream (75ml) – Adds gloss and richness.
• Warm Water (240ml total) – Split for blooming the gelatin and thinning the glaze.
• Dark Chocolate (55g) – Melts into the glaze for extra smoothness and depth.

MAKING IT YOURS (WITHOUT RUINING IT)

• Want to flavour the sponge? Add 1 tsp vanilla or espresso powder for subtle depth.
• No dark chocolate? Semi-sweet works, but it won’t be as intense.
• Gluten-Free? I tested with a 1:1 GF flour blend—it worked, though the sponge was a little more fragile.
• Need a shortcut? You can use a boxed sponge if it’s sturdy—avoid anything too crumbly or soft.

MISTAKES I’VE MADE (AND HOW TO AVOID THEM)

What Went Wrong	Why It Happens	How to Fix It
Glaze too runny	Didn’t cool long enough	Let it thicken 10–15 mins before pouring
Bubbles in glaze	Whisked too hard or didn’t sieve	Gently stir and always strain before using
Sponge collapsed	Didn’t beat eggs long enough	Whip to ribbon stage—thick, pale, and voluminous

HOW TO MAKE MARY BERRY’S CHOCOLATE MIRROR CAKE

1. Preheat the Oven
Set oven to 180°C (350°F). Grease and line a 9-inch springform tin.

2. Make the Sponge
Whisk eggs and sugar until thick and pale (ribbon stage). Sift in flour, baking powder, and salt. Fold gently to keep the air. Drizzle melted butter around the edge of the bowl and fold it in.

3. Bake
Pour into the tin and level. Bake 30 mins until pale golden and edges pull away. Cool in the tin briefly, then transfer to a wire rack.

4. Prepare the Gelatin
Bloom gelatin in 120ml warm water. Stir and leave to thicken (don’t boil).

5. Make the Glaze
In a saucepan, heat sugar, cocoa, cream, and 120ml warm water. Bring just to a boil, then stir in chocolate until smooth.

6. Finish the Glaze
Stir in bloomed gelatin. Strain through a sieve into a bowl. Let cool for 15 mins until thick but pourable.

7. Glaze the Cake
Place cake on a wire rack over a tray. Slowly pour glaze over the centre, letting it drip down the sides. Use a palette knife to gently cover any missed spots. Let set 30 mins before transferring.

TIPS FROM MY KITCHEN

• I chill the sponge in the fridge before glazing—it sets the surface and helps the glaze cling.
• I always use a digital thermometer: glaze should be about 30–35°C when pouring for best shine.
• I strain the glaze twice—once into the bowl, then again before pouring. Super smooth finish.

STORAGE + SERVING

• Fridge: Keeps 3 days in a covered container. Shine holds up surprisingly well.
• Freezer: Freeze sponge only. Glaze once thawed for best results.
• Serve with: Whipped cream or raspberry purée for a little tartness.

FREQUENTLY ASKED QUESTIONS

Q: Can I make this ahead?
A: Yes! Bake the sponge a day ahead and glaze the next day. Just chill the cake before glazing.

Q: My glaze isn’t shiny—what went wrong?
A: It was either too cool when poured or over-stirred. Aim for about 32°C and minimal mixing.

Q: Can I double the glaze for a thicker coat?
A: No need—it’s designed to be a thin, smooth layer. Too thick and it’ll slump or crack.

Q: Can I use agar instead of gelatin?
A: You can, but the shine isn’t quite as intense. Gelatin really gives that glassy finish.

Try More Recipes:

• Mary Berry American Chocolate Cake
• Mary Berry Tiny Chocolate Cupcakes
• Mary Berry Chocolate Yoghurt Cake