Colin The Caterpillar Traybake (No Bake)

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My Colin the Caterpillar traybake is the ultimate kids' birthday party dessert! It's a super easy, no-bake biscuit slice with a chocolate bourbon base and white chocolate fudge topping.

squares of no bake colin the caterpillar traybake slice on a plate

After taking one bite of my delicious Percy Pig traybake, I was STRAIGHT down to M&S to get ingredients for a Colin the Caterpillar traybake!

It's the same simple idea (a biscuit base with fudge topping) but with a cute Colin twist. This is actually one of my favourite biscuit slice recipes I've ever made, because I just love the combo of milk and white chocolate so much!

This no-bake traybake is a great alternative to a Colin the Caterpillar cake for those who want to do a little easy 'baking' for a special event. I think it'd be perfect for kids' birthdays, picnics, bake sales or even Father's Day. I hope you enjoy the recipe!

Ingredients

Bourbon biscuits: I chose to do a chocolate base and a white fudge topping, but if you prefer, you can do a neutral base with digestive biscuits or a white base with Custard Cream biscuits.
Condensed milk: A 397g tin. Make sure to get the sweetened one, not evaporated milk. Read about the difference here: Evaporated Milk Vs Condensed Milk.
Butter: Use real butter, not 'buttery spread' or margarine. This will help it set firm and fudgy!
White chocolate: For our fudge topping. Again, feel free to mix it up here! You can use an equal amount of milk or dark chocolate to create more of a contrast with the Colin sweets.
Colin the Caterpillar Greatest Bits: This is a bag of white chocolate Colin faces, as well as some white chocolate 'shoes' and colourful candy-coated chocolate beans. You'll get enough faces in one bag to decorate your traybake.
Sprinkles: Optional but cute!

Equipment

8x8-inch tin: As always, if you want to use a different tin size than my recipe calls for, make sure to use my cake pan converter to adjust the quantities to fit.
Baking paper: I like to leave some hanging over the edges for easy removal later. This ensures the fudge won't stick to the sides of the tin.
Saucepan: For melting the white chocolate and condensed milk together to create the topping.
Mixing bowl: One that's large enough to let you properly mix the biscuits in with the butter and condensed milk.
Utensils: A wooden spoon, a silicone spatula, and a sharp knife.
Food scale: For best results, measure everything accurately with a scale rather than estimating with cups or oz (except the condensed milk, which should be measured in ml).
Measuring cup: A ½ cup (125ml) is handy for measuring the condensed milk but a measuring jug or even tablespoons will work fine too.

slices of colin the caterpillar chocolate traybake biscuit slice on a white surface

How to make Colin the Caterpillar Traybake

Step 1: First, line an 8x8-inch tin with baking paper. Check out my post on how to line a traybake tin if you need help with this.

Step 2: Next, let's prepare the base. Add 450g bourbon biscuits to a food processor or powerful blender and blitz them up until you have fine crumbs. Run your hands through them to check there are no big lumps left, as this can stop the base from setting firmly.

Step 3: Pour the biscuit crumbs into a bowl then add in 150g melted butter and 120ml condensed milk. Mix well until all the crumbs are covered, with no dry or sticky bits left. Press this mixture into your lined tin.

chocolate biscuit mixture in a glass bowl

Step 4: Add 250g white chocolate to a saucepan along with what's left in the tin of condensed milk (~277ml). Place it over low heat on the stove and stir gently until it's melted, thick and glossy, with no lumps left.

Step 5: Pour the fudge over the biscuit base in the tin and gently spread it out to the edges.

white chocolate fudge topping being poured onto chocolate biscuit base

Step 6: Decorate with Colin the Caterpillar faces, chocolate beans and sprinkles. Once you're happy with the way it looks, pop the traybake in the fridge for 4 hours to set.

adding chocolate colin the caterpillar faces and colourful beans on top of the no bake biscuit slice

Step 7: Once set, remove it from the tin, cut it into slices and enjoy!

Top tips

The Colin faces will melt slightly when you add them to the fudge topping, so be careful not to move them around too much once placed. If you want to prevent this completely, freeze the faces for an hour or two before you start.
If you fancy using the gummy Colin sweets instead of the chocolate faces, I think they'd taste best paired with my Jammie Dodger traybake.
Add a drop of your favourite food colouring for a fun, vibrant fudge topping.

FAQs

How long will Colin the Caterpillar traybake last?

This will keep well in an airtight container for around 1 week. It's best kept in the fridge as the butter needs to stay cool to keep the base nice and firm.

Can I freeze this recipe?

Yes, this can be frozen for up to 3 months in airtight containers or wrapped tightly in foil or clingfilm. To defrost, transfer it to the fridge overnight or let it sit out at room temperature for an hour or so. Do not refreeze.

Why is my base falling apart?

This can happen if your biscuits are not crushed finely enough or if you've incorrectly measured the condensed milk. Use a measuring cup to get 120ml rather than weighing out 120g on a scale (which is only 90ml).

overhead image of slices of colin the caterpillar traybake

More no-bake traybakes:

I hope you like this gorgeous Colin the Caterpillar dessert! If you try it at home, please leave me a comment and rating below to let me know what you think. Enjoy!