Our Thermomix Weet-Bix Slice is made using just a handful of basic pantry ingredients and takes just 10 minutes to prepare!
An all-time favourite slice with the kids (and adults too).

This Thermomix Weet-Bix Slice recipe is one of the oldest AND the most popular on our website!
Not only does it make a great treat for the kids, it's also freezer friendly which means you'll have easy snacks ready to grab and go.
It's also a yummy addition to kids lunch boxes too (it's always the first thing to disappear).

Why You'll Love This Recipe
- Basic ingredients - you just need a few basic pantry and fridge ingredients to put this Thermomix Weet-Bix Slice together.
- Freezer Friendly - this slice can be frozen for up to 3 months. Simply place frozen pieces directly into school lunch boxes and they'll be defrosted by recess time.
- Quick & Easy - it takes just 10 minutes of active preparation to make this yummy chocolate slice.
- Budget-Friendly - this recipe is made using cheap ingredients (and it's also a great way to use up Weet-Bix crumbs at the bottom of the box!)
- Versatile - you can decorate your slice with sprinkles/100s and 1000s, coconut, Milo or simply leave it plain.
What You Need
All you need is a few pantry/fridge staple ingredients to make our Thermomix Weet-Bix Slice!
Please scroll to the recipe card at the bottom of the post for the ingredient quantities and the full detailed method.

To make this classic slice, you will need:
- Weet-Bix - if you have a box of Weet-Bix in the cupboard, you're ready to make this slice! It's also the perfect way for using up all of the crumbs at the bottom of the box
- Butter - choose salted or unsalted butter
- Cocoa Powder - use unsweetened cocoa powder or cacao powder
- Brown Sugar - light or dark brown sugar can be used. This gives the slice a delicious chewy texture.
- Desiccated Coconut - fine dry coconut
- Egg - use a large egg (approximately 60g)
- Icing Sugar - you can use either icing sugar mixture or pure icing sugar for this recipe. Icing sugar mixture sets softer than pure icing sugar. If you're planning to send our Thermomix Weet-Bix Slice to school in lunch boxes, I would recommend using pure icing sugar.
Step By Step Instructions
Our Thermomix Weet-Bix Slice is so easy to make in your Thermomix:
Please scroll to the recipe card at the bottom of the post for the ingredient quantities and the full detailed method.
Step 1 - Crush The Weet-Bix

Crush the Weet-Bix and set aside in a seperate bowl until needed.
Step 2 - Melt The Butter

Place the chopped butter into the Thermomix machine and melt.
Step 3 - Mix

Add the crushed Weet-Bix, brown sugar, cocoa powder, coconut and egg and mix until well combined.
Step 4 - Bake
Press the mixture into the prepared slice tin and bake.
Step 5 - Make The Icing
Place all of the icing ingredients into a clean and dry Thermomix bowl and mix together.
Pour over the slice and decorate with sprinkles/100s and 1000s.

Expert Tips
- It's completely fine for there to be a little melted butter remaining on top of the slice when it comes out of the oven. It will disappear very quickly.
- When you are making this recipe, it's important to make sure you allow the slice to cool completely before adding the icing, otherwise it will be impossible to spread.
- Place the slice into the fridge or freezer to hurry up the cooling process before adding the icing.
- Store in an airtight container and store in the fridge for up to 1 week.
- This slice can be frozen in an airtight container for up to 3 months.
FAQs
Weet-Bix are a popular breakfast cereal here in Australia and New Zealand made from wholewheat and shaped into bars. If you cannot find 'WeetBix' you can also use Vita Brits or similar cereals.
Of course! You can use the conventional instructions listed here.
You sure can! It's been tested over and over in all models of the Thermomix.

Related Recipes
Love our easy kid-friendly slices?
Here's a few more of our most popular lunch box slice recipes:

Thermomix Weet-Bix Slice
Equipment
- 28 x 18cm slice tin
- Thermomix
- Oven
Ingredients
- 200 g Weet-Bix approx 12 Weet-Bix
- 200 g butter unsalted
- 30 g cocoa powder
- 150 g brown sugar
- 30 g desiccated coconut
- 1 egg
Chocolate Icing
- 225 g icing sugar
- 1 tablespoon cocoa
- 1 teaspoon butter
- 2 tablespoon boiling water
- 100s and 1000s or sprinkles
Instructions
- Preheat oven to 160 degrees celsius (fan-forced) and line an 18 x 28cm slice tray with baking paper.
- Place the Weet-Bix into the Thermomix bowl and mix for 10 seconds, Speed 7 until finely crushed. Transfer the Weet-Bix crumbs to a seperate bowl and set aside until needed.
- Without washing the bowl, place the butter into the Thermomix bowl and melt for 3 minutes, 60 degrees, Speed 2.
- Add the crushed Weet-Bix, cocoa powder, brown sugar, coconut and egg and mix for 10 seconds, Speed 4. Scrape down the sides of the bowl and mix for a further 10 seconds, Speed 4.
- Transfer the mixture to your prepared slice tray and cook for 18 - 20 minutes, or until the slice is firm to the touch.
- Allow the slice to cool completely in the tin before preparing the icing. Place all of the icing ingredients into a clean and dry Thermomix bowl and mix for 30 seconds, Speed 3. Scrape down the sides of the bowl and mix for a further 20 seconds, Speed 3 or until smooth.
- Pour the icing over the completely cooled slice and use a butter knife to smooth. Decorate with 100s and 1000s or sprinkles.
Notes
- It's completely fine for there to be a little melted butter remaining on top of the slice when it comes out of the oven. It will disappear very quickly.
- When you are making this recipe, it's important to make sure you allow the slice to cool completely before adding the icing, otherwise it will be impossible to spread.
- Place the slice into the fridge or freezer to hurry up the cooling process before adding the icing.
- Store in an airtight container and store in the fridge for up to 1 week.
- This slice can be frozen in an airtight container for up to 3 months.
Nutrition
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