Mary Berry Celebration Chocolate Mousse Cake

I made this one for my mum’s birthday, thinking I’d get ahead by prepping it the night before. Big mistake—I forgot the mousse needs the full chill to set properly. The next morning, the top looked like a chocolate swamp. Don’t worry, I rescued it with a quick pop in the freezer (more on that trick later). But truly, this cake is a showstopper if you give it the time it asks for.

It’s got that classic Mary Berry ease in the sponge, but it’s the mousse—dense but airy, rich but not cloying—that takes it into “celebration cake” territory. If you’ve ever wanted something that looks posh but doesn’t involve six layers and a sugar thermometer, this is the one. Let me show you how I fixed the mousse drama and nailed the texture the second time around.

Why This One Works So Well

Most mousse cakes lean either too fluffy (falls apart when sliced) or too firm (like a chocolate brick). Mary’s version hits the middle perfectly, and it’s mostly down to two things:

• The cake is just one layer—no stacking stress—and it’s dense enough to support the mousse but still soft.
• The mousse gets its richness from real whipped cream, not gelatin or eggs, so the texture stays cloud-like if you don’t overwhip.

Also: the brandy on the warm sponge? Game-changer. I nearly skipped it (mum doesn’t like booze in cake), but it added just the right depth without tasting boozy.

INGREDIENTS + WHY THEY MATTER

• Cocoa Powder (25g) – Forms the base of the sponge. Must be proper unsweetened cocoa—don’t use drinking chocolate, or the cake will taste flat.
• Boiling Water – Activates the cocoa, deepens the flavour. It’s a small step but critical.
• Caster Sugar – Keeps the crumb light and sweet without being claggy.
• Self-Raising Flour + Baking Powder – The combo gives a gentle lift. I once used plain flour by mistake… ended up with a chocolate puck.
• Baking Spread (Stork or similar) – Easy to cream, stays soft from fridge to oven. Butter works too, but makes the sponge a bit denser.
• Dark Chocolate (300g, 40–50%) – This is non-negotiable. Too bitter (70%+) and the mousse is chalky. Too sweet and it’s sickly.
• Whipping Cream (450ml) – Needs to be cold and only whipped to soft peaks. I’ve overwhipped before—it looked like chocolate cottage cheese.

WANT TO CHANGE IT UP? HERE’S HOW

• No Brandy? Skip it, or sub with a splash of coffee or orange juice. Coffee was lovely, actually—bit like tiramisu.
• Gluten-Free? I tried it with a GF self-raising blend and it worked fine. Just don’t overbake—GF dries out faster.
• Dairy-Free? Haven’t fully cracked this, but I tested with oat cream for the mousse once. It set okay, but lacked richness.
• Fruit Swap – Strawberries work, but they leak juice fast. Stick to raspberries or blueberries for prettiness + texture.

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

What Went Wrong	Why It Happens	How to Fix It
Mousse wouldn’t set	Chocolate was too warm or cream too soft	Let chocolate cool slightly; whip cream to just-soft peaks
Cake too dense	Forgot baking powder	Double check flour isn’t plain
Soggy mousse layer	Cake wasn’t fully cooled	Let cake cool completely before topping
Bitter mousse	Used 70% dark chocolate	Stick to 40–50% cocoa solids

HOW TO MAKE MARY BERRY’S CELEBRATION CHOCOLATE MOUSSE CAKE

1. Prep the tin – Line a deep 20cm springform tin all the way up the sides. The mousse rises higher than you think.
2. Make the cake – Mix cocoa and boiling water to a paste. Add sugar, flour, baking powder, baking spread, eggs. Beat until smooth. Bake at 160°C fan for 20–25 mins.
3. Soak the sponge – While warm, brush on the brandy. Cool completely in the tin.
4. Make the mousse – Melt chocolate gently, then cool. Whip cream till soft peaks. Fold chocolate into cream—do NOT rush this. It should be glossy and mousse-like.
5. Assemble – Spoon mousse over sponge, level the top, cover, and chill overnight.
6. Finish + serve – Dust with cocoa. Top with berries. Slice with a warm knife. Serve with pouring cream.

TIPS FROM MY KITCHEN

• I wrap the base of my tin in foil when chilling—helps insulate and prevent fridge smells getting in.
• Use a silicone spatula for folding the mousse—less deflation than a whisk or spoon.
• If the mousse is too soft after 4 hours, stick it in the freezer for 20 mins before serving.

STORAGE + SERVING

• Fridge: Keeps beautifully for 3–4 days in an airtight container.
• Freezer: Not ideal—the mousse texture changes. Emergency freezer-firming is fine, but don’t freeze long term.
• Serve with: Pouring cream, fresh berries, or a sharp raspberry coulis. Ice cream is too much, trust me.

FREQUENTLY ASKED QUESTIONS

Q: Can I make it ahead?
A: Absolutely—best made the day before. Just wait to add berries until just before serving so they don’t bleed juice.

Q: Can I skip the mousse and just make the sponge?
A: You can, but then it’s just a basic chocolate sponge. The mousse is the star here.

Q: What’s the best chocolate to use?
A: I love Lindt 50% or Green & Black’s Dark Cooking Chocolate. Avoid anything marked “compound chocolate” or it’ll go grainy.

Q: Do I need a springform tin?
A: Yes. You won’t get it out neatly otherwise. The mousse clings to everything.

Try More Recipes:

• Mary Berry Chocolate Roulade Recipe
• Mary Berry Chocolate Victoria Sandwich
• Mary Berry Cut And Come Again Cake​
• Mary Berry Coffee Victoria Sandwich