I remember staring into my fridge one summer afternoon, craving something sweet and creamy, but the thought of turning on my oven felt like a crime. It was just too hot. That’s when I remembered this old-school treat, the kind you’d see at a church bake sale or in your grandma’s recipe box.
This is the ultimate no-bake custard slice. I’m going to show you how to make a ridiculously easy version that tastes like it came from a fancy bakery. You’ll get a crunchy biscuit base, a silky smooth custard filling, and a simple chocolate topping that sets perfectly.
This isn’t about being a perfect baker. It’s about making something delicious with zero stress.
What You’ll Need
Getting your ingredients ready first is half the battle. It makes everything go so much smoother, trust me. I’ve laid it all out for you here. No guessing games.
For the Biscuit Base
This is the crunchy foundation. It’s simple, but getting the ratio right is key so it doesn’t fall apart when you slice it.
| Ingredient | Amount |
|---|---|
| Plain sweet biscuits (like Marie or Arrowroot) | 250g (1 packet) |
| Unsalted butter | 125g (½ cup) |
For the Creamy Custard Filling
Here’s the star of the show. We’re using custard powder because it’s the secret to a perfect set without any eggs or baking. It’s basically magic yellow dust.
| Ingredient | Amount |
|---|---|
| Custard powder | ½ cup |
| Caster sugar (or superfine sugar) | ½ cup |
| Whole milk | 3 cups |
| Unsalted butter, extra | 1 tbsp |
| Vanilla extract | 1 tsp |
For the Simple Chocolate Icing
You don’t need a fancy ganache. This simple icing is sweet, chocolatey, and sets with a nice, soft bite. It’s the perfect finishing touch.
| Ingredient | Amount |
|---|---|
| Icing sugar (powdered sugar), sifted | 1 ½ cups |
| Unsweetened cocoa powder, sifted | 3 tbsp |
| Unsalted butter, melted | 2 tbsp |
| Boiling water | 2-3 tbsp |
The Tools for the Job
You don’t need any wild kitchen gadgets. I bet you have all of this stuff already.
- A square baking pan: An 8×8 inch (or 20×20 cm) pan is perfect.
- Parchment paper: To line the pan so you can lift the slice out easily. This is a non-negotiable step.
- Food processor or a ziplock bag and rolling pin: To crush those biscuits.
- A medium saucepan: For making the custard.
- A whisk: Your best friend for lump-free custard.
- Spatula: For spreading everything evenly.
- Measuring cups and spoons: For accuracy!
Let’s Make a No-Bake Custard Slice
Alright, let’s get into it. Read through the steps once before you start, just so you know what’s coming. It helps, I promise.
Step 1: Prep Your Pan
First things first, line your 8×8 inch pan with parchment paper. Leave a little bit of paper hanging over the sides. These will be your “handles” to lift the whole thing out later. It’s a game-changer for getting clean slices.
Step 2: Make the Biscuit Base
Crush your biscuits until they look like coarse sand. A food processor makes this super quick, but whacking them in a bag with a rolling pin is honestly more fun. Melt your 125g of butter, then pour it into the biscuit crumbs and mix it all up until it looks like wet sand.
Step 3: Press the Base
Dump the buttery crumbs into your prepared pan. Now, press them down firmly and evenly. I use the bottom of a glass to really pack it in there. You want it to be compact. Pop the pan in the fridge to chill while you make the custard.
Step 4: Start the Custard
In a small bowl, mix the ½ cup of custard powder and ½ cup of sugar together. Add about ¼ cup of the cold milk to this and whisk it until it’s a smooth, lump-free paste. This little step is the number one secret to smooth custard. Don’t skip it.
Step 5: Heat the Milk
Pour the rest of the milk into your saucepan and heat it over medium heat until it’s hot and steaming. You don’t want it to boil over, so just watch for little bubbles around the edge of the pan.
Step 6: Thicken the Custard
Okay, time to put it all together. Slowly pour the hot milk into your custard paste bowl, whisking the whole time. Once it’s combined, pour everything back into the saucepan. Cook it over medium heat, whisking constantly. It will look thin at first, then suddenly it will get super thick. This takes about 3-5 minutes. Keep whisking!
Step 7: Finish the Custard
Once it’s nice and thick, take it off the heat. Stir in the extra 1 tbsp of butter and the vanilla extract. The butter adds a little richness and shine.
Step 8: Assemble and Chill
Grab your pan with the chilled base from the fridge. Pour the hot custard over the base and spread it out evenly with a spatula. Now, here’s a tip: press a piece of plastic wrap directly onto the surface of the custard. This stops a rubbery “skin” from forming. Let it cool on the counter for a bit, then put it in the fridge for at least 3 hours to set completely. It needs to be firm to the touch.
Step 9: Make the Icing
Once the custard is totally set, you can make the icing. In a bowl, mix your sifted icing sugar and sifted cocoa powder. Add the melted butter and 2 tablespoons of boiling water. Mix it until it’s smooth. If it’s too thick, add that last tablespoon of water. You want it to be spreadable, not runny.
Step 10: Ice and Final Chill
Pour the chocolate icing over the set custard. Work quickly to spread it into an even layer because it will start to set up. Pop the whole thing back in the fridge for another 30 minutes, or until the icing is firm.
Step 11: Slice and Serve
This is the moment of truth. Lift the entire slice out of the pan using your parchment paper handles. To get super clean cuts, fill a jug with hot water and dip a sharp knife into it. Wipe the knife clean between each cut. Slice it into squares and you’re done!
Pro Tips from My Kitchen
I’ve made this dessert more times than I can count. Here are a few things I’ve learned that make a real difference.
- The Custard Paste is Everything. I mentioned it before, but it’s worth saying again. Mixing the custard powder with a little cold milk before adding the hot milk is the golden rule. It allows the starch to dissolve without heat, which prevents lumps from ever forming. If you just dump the powder into hot milk, you’re asking for trouble.
- Don’t Rush the Chill Time. I know it’s tempting to cut into it early, but you have to let each layer set properly. If the base is still warm, the custard can make it soggy. If the custard isn’t fully set, the icing will make a mess and you’ll get sloppy slices. Patience is an ingredient here.
- Use a Hot Knife for Slicing. This is my go-to trick for any layered bar or slice. A cold knife will drag through the layers and make a mess. A hot, clean knife melts through the icing and custard just enough to give you a perfect, professional-looking edge. It’s a small step that makes a huge visual impact.
- Sift Your Icing Ingredients. It seems like an annoying extra step, but sifting the icing sugar and cocoa powder is the only way to guarantee a silky smooth icing. Both tend to have little hard lumps that won’t dissolve, and you’ll feel them. Take the extra 30 seconds to sift.
Substitutions and Fun Variations
Once you have the basic recipe down, you can start playing around with it. It’s pretty forgiving.
- Biscuit Swaps: You can use almost any plain, dry biscuit. Digestive biscuits give it a nice whole-wheat flavor. Graham crackers are classic. For a chocolatey twist, use chocolate ripple biscuits for the base.
- Gluten-Free Version: Just use your favorite gluten-free plain sweet biscuits for the base. The rest of the ingredients are typically gluten-free, but always double-check your custard powder label to be sure.
- Lemon Custard Slice: This is a great one. Add the finely grated zest of one lemon to the custard when you add the vanilla. For the topping, skip the chocolate and make a simple lemon glaze with icing sugar and lemon juice.
- Caramel Layer: Before you pour the custard on, you can spread a thin layer of canned caramel (like Carnation’s) over the biscuit base. It adds a whole other level of deliciousness.
- Coffee Flavor: Dissolve a teaspoon of instant espresso powder in the hot milk before you make the custard for a mocha vibe. It goes so well with the chocolate icing.
Leftovers and Storage
If you actually have leftovers, storing them is easy.
Keep the custard slice in an airtight container in the fridge. It will stay fresh for up to 4 days. The biscuit base might soften a little bit by day 4, but it will still be amazing.
I wouldn’t recommend freezing it. The custard can get a weird, watery texture when it thaws. This is one of those desserts that’s best made and eaten within a few days.
Frequently Asked Questions
Here are some questions I get asked all the time.
Q1. My custard is lumpy! What did I do wrong?
Ans: You probably skipped making the paste first. Mixing custard powder directly into hot liquid is the fastest way to get lumps. Always mix it with a little cold milk first.
Q2. Why didn’t my custard set?
Ans: It either wasn’t cooked long enough on the stove, or it didn’t have enough time to chill in the fridge. You need to whisk it on the heat until it’s properly thick, then give it at least 3 hours in the fridge.
Q3. Can I use real egg custard instead of powder?
Ans: You could, but that would make it a baked custard tart, not a no-bake slice. The beauty of this recipe is its simplicity, which comes from the custard powder.
Q4. My biscuit base is too crumbly. How can I fix it?
Ans: This usually means there wasn’t quite enough butter, or it wasn’t packed down firmly enough. Make sure you’re really pressing it into the pan to compact it.
Wrapping Up
See? That wasn’t so hard. You just made a classic, crowd-pleasing dessert without even looking at your oven. The combination of that crunchy base, the cool and creamy custard, and the sweet chocolate top is just perfect.
It’s the kind of recipe you’ll make again and again for family get-togethers, potlucks, or just because it’s a Tuesday and you deserve a treat.
Now it’s your turn. Give it a try and let me know how it goes in the comments below. Did you try any variations? Did you run into any trouble? I’d love to hear all about it. Happy (no) baking