Mary Berry Custard Slice Recipe

There’s something utterly proper about a Mary Berry custard slice, isn’t there? It takes me right back to my nan’s kitchen on a Sunday afternoon — sun filtering through the lace curtains, the air thick with the smell of vanilla and warm pastry. She’d cut us each a square, fingers sticky with icing before we’d even finished the first bite. That crisp puff pastry, that silken custard, and that simple zigzag of feathered chocolate — a quiet luxury of British baking.

This isn’t just a custard slice. It’s the custard slice. The kind that makes you pause between bites. And yes, the recipe takes a little time, but it’s the sort of baking that’s worth every chilled moment. Let’s walk through this beauty together — from the puff to the patisserie cream.

Ingredients List

For the Rough Puff Pastry:

• 225g plain flour — plus extra for dusting
• ½ tsp salt
• 200g chilled butter — cut into 1cm cubes; those cold lumps create glorious flake
• 140–160ml cold water — add slowly, you might not need it all

For the Crème Pâtissière:

• 500ml whole milk
• 1 vanilla pod — split and scraped; proper custard starts with real vanilla
• 100g caster sugar
• 4 egg yolks — save the whites for a cheeky meringue later
• 40g cornflour — thickens without dulling the flavour
• 40g butter

For the Icing:

• 200g icing sugar
• 5 tsp water
• 50g dark chocolate — melted, for that lovely feathered finish

How To Make It (Instructions)

1. In a large bowl, mix flour and salt. Rub in a third of the butter till it looks like crumbs. The rest? Leave in bold, cold lumps — that’s your flake insurance.

2. Slowly add water, stirring gently until a soft dough forms. Don’t overdo it.

3. Roll it into a rectangle about 2.5cm thick. Fold the bottom third up, then the top third down. It’s like tucking in a blanket.

4. Wrap and chill for 10 minutes. Then repeat the roll, fold, chill three times. Yes, it’s a bit of a dance — but a necessary one.

5. While that chills, make your crème pâtissière. In a bowl, whisk egg yolks, sugar, and cornflour till smooth.

6. Heat milk and vanilla pod (plus seeds) in a saucepan. Just to simmer — not a full boil.

7. Slowly pour the hot milk into your yolk mixture, whisking constantly so no scrambled eggs sneak in.

8. Return to the pan and cook gently, stirring until it thickens like rich pudding. Take off heat and stir in butter. Cover with cling film touching the surface to prevent a skin, then chill.

9. Preheat oven to 220°C (425°F). Line two trays with baking paper.

10. Cut pastry dough in half, roll each to 20cm x 8in x 5mm. Chill them for 10-15 mins — trust me, it helps with rise.

11. Bake the pastry sheets for 15–20 mins or until crisp and golden. Cool completely.

12. Line a square tin with foil. Place one pastry sheet in the bottom. Spread crème pâtissière over — smooth and even.

13. Top with second pastry sheet, press gently. Chill while you make the icing.

14. Mix icing sugar and water till smooth and pourable. Spread over the top layer of pastry.

15. Pipe chocolate lines across the top. Then, drag a toothpick through the lines in alternate directions for that gorgeous feathering.

16. Chill until fully set — about 1–2 hours. Slice into squares (wipe your knife between cuts!) and serve.

And yes, I always forget to feather the chocolate till it’s half-set. Still tastes fab, just less photogenic.

Common Mistakes

Why is my pastry soggy on the bottom?
Your custard was likely too warm when added — always chill it before assembling.

How do I avoid lumpy custard?
Whisk continuously and temper your eggs with warm milk. I’ve scrambled it more than I’d care to admit.

Why doesn’t my icing stay white?
If your chocolate bleeds into it, it’s probably too hot. Let it cool slightly before piping.

Why is my custard too runny?
You may not have cooked it long enough. It should be thick enough to coat the back of a spoon.

Storage and Reheating Tips

In the fridge:
Store slices in an airtight container. They’re best within 2–3 days — any longer and the pastry starts to wilt.

In the freezer:
Wrap each slice in cling film and foil. Freeze for up to 2 months. Thaw overnight in the fridge, don’t rush it.

Reheating:
Honestly? Don’t. Custard slice is best cold. But if you must, pop it in the microwave for 10 seconds max — just enough to take the chill off.

What To Serve With It

• Strong black tea or espresso — Cuts the richness, and it’s just… classic.
• Fresh raspberries — A little tart pop alongside the creamy slice.
• A dollop of whipped cream — If you’re feeling extra indulgent.

FAQ Section

Can I make this gluten-free?
Yes, use a gluten-free flour blend for the pastry. But be gentle — gluten-free dough is more delicate to work with.

Can I use store-bought puff pastry?
Absolutely. It won’t be quite as airy as homemade, but it saves time and still tastes smashing.

Can I make it the night before?
Yes, and it’s better that way. Chilling overnight helps it set beautifully and slice cleanly.

How long does homemade crème pâtissière last?
About 3 days in the fridge — always covered tightly with cling film on the surface.

Try More Recipes:

• Mary Berry Double Chocolate Chip Muffins
• Mary Berry Blueberry Loaf Cake
• Mary Berry Coconut Pyramids