Caramel Oat Slice

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The easiest and most delicious Caramel Oat Slice! Crunchy crumble layers filled with homemade sweet and creamy caramel.

This dreamy slice can be prepped in a few easy steps, and ready in less than an hour, but it should come with a warning - it's highly addictive!

Three squares of caramel crumble slice stacked together.

Caramel oat slice is a divine combination of texture and flavour, with its buttery caramel layer sandwiched between a sweet oat crumble.

Serve with a cuppa, pop in a lunchbox, or enjoy as a luscious warm dessert with a scoop of ice cream, or a drizzle of cream.

This caramel oat slice has the same base and topping as my creamy lemon crumble bars and lemon and blueberry crumble slice, and has the same caramel filling as my ever popular chocolate caramel slice.

Why You're Going To Love This Recipe

I don't know many who can resist a crunchy and chewy oat crumble, and with a layer of sweet caramel in between, you have a totally irresistable slice to serve!

Basic baking ingredients - this caramel oat slice uses only basic pantry and fridge items, and rolled oats would have to be one of the most economical and versatile ingredients to have in the cupboard. They're not just a breakfast food!
Homemade always tastes best - it's true! Freshly baked and homemade always wins the 'taste test' over bought cakes and biscuits, plus you know exactly what's in it... no sneaky additives.
Keeps well - stored in an airtight container in the fridge, this caramel oat slice will last up to a week (yet it's highly unlikely to last that long in my house!), and if there happens to be any left, just pop into a container and freeze for another time. This slice defrosts well.
Versatile - enjoy caramel crumble bars as a slice, or warm it up and serve as a luscious dessert.....mmmm....
Conventional and Thermomix - I've included both simple methods in the post and recipe card.

Looking down on squares of caramel crumble bars on a white plate.

What You Need

If you love caramel and sweet crumbles, I guarantee you'll adore this caramel oat slice.

Note: Scroll to the recipe card at the bottom for the ingredients quantities and full detailed method.

For The Crumble Base & Topping

Plain flour - also known as all-purpose flour.
Rolled oats - full of fibre and health benefits, rolled oats are like a 'superfood', and they're as cheap as chips! So handy as a baking ingredient.
Salt - just a pinch.
Bicarbonate of soda - also known as baking soda. In Australia, we tend to use the name bicarbonate of soda (or bicarb soda for short), whereas overseas it is often known as baking soda.
Raw sugar - gives a good crunch to the base and crumble topping.
Brown sugar - choose either regular light brown sugar or dark brown sugar.
Butter.
Vanilla extract - use a good quality brand of vanilla extract, such as Queens, that has been extracted from the vanilla bean, and not synthetically flavoured.

For The Caramel Filling

Sweetened condensed milk - I recommend using the full fat version of sweetened condensed milk as the 'skim' version will not set the caramel as well.
Golden syrup - is a common baking ingredient in Australia and New Zealand. If you can’t buy golden syrup, you can replace it with corn syrup, honey or maple syrup.
Butter.

Ingredients for caramel oat slice set out on a bench top.

Equipment Required

Besides the usual mixing bowl and spoon, there's little equipment required to make this scrumptious caramel oat slice.

Baking tin - 18cm x 28cm slice tray, lined with baking paper.
Saucepan and stove top, or Thermomix (optional).

Squares of an oat crumble with caramel filling.

Step By Step Instructions

The same oat mixture is used for both the base as well as for the crumble on top, which makes this caramel oat slice even easier to assemble. You can make the caramel filling while the base cooks.

Note: Scroll to the recipe card at the bottom for the ingredients quantities and full detailed method.

Step 1 - Prepare The Base Mixture

Preheat the oven to 160 degrees celsius (fan forced).

Grease and line your baking tray, allowing the edges of the baking paper to overhang.

In a large bowl, place the plain flour, rolled oats, salt and bi-carbonate of soda and mix together. Stir through the raw sugar and brown sugar and once again, combine the dry ingredients well.

Flour, rolled oats, bicarb of soda and sugars in a white mixing bowl.

Add vanilla extract and melted butter to the dry ingredients and mix together well.

If using a Thermomix: Melt the butter and vanilla extract for 3 minutes, Speed 2, 80 degrees. Add the plain flour, rolled oats, salt, bi-carbonate of soda, brown sugar and raw sugar. Mix for 20 seconds on Reverse, Speed 2. Scrape down the sides. Mix for a further 20 seconds on Reverse, Speed 2.

Crumble mix after melted butter added to flour and sugar.

Press just over half of the crumble mixture into the base of the prepared tin and use the back of a spoon to smooth the mixture into an even layer.

Half the crumble mix pressed into a paper lined slice tray.

Bake in the preheated oven for 15 minutes, until golden.

Once baked, remove from the oven and set aside, but leave the oven on to finish baking once the caramel layer and crumble topping has been added.

Step 2 - Make The Caramel Filling

Place the golden syrup, condensed milk and butter into a small saucepan over low heat.

Sweetened condensed milk, golden syrup and butter in a small saucepan.

Stir continuously for 10-15 minutes or until the caramel has thickened (make sure your heat is very low and continue stirring until the sauce has obviously thickened).

If using a Thermomix: Place the golden syrup, sweetened condensed milk and butter into a clean and dry Thermomix bowl. Mix for 8 minutes, 80 degrees, Speed 4.

Melted butter mixed with condensed milk and golden syrup in a saucepan.

Pour the caramel mixture over the cooked base.

Thick caramel mix poured over baked base in a baking tray.

Step 3 - Add Crumble Topping And Bake

Sprinkle the remaining crumble mixture over the top of the caramel filling.

Bake in the oven for 20 - 25 minutes or until lightly golden.

Remaining crumble mix pressed over caramel layer.

Cover and refrigerate for at least 2 hours (preferably overnight) then take it out and cut into squares.

Expert Tips

Caramel oat slice - easy to put together, hard to resist!

All ovens are different - the slice is ready when the crumble is golden. I specify degrees celsius (fan-forced) for my recipes. If you're using a conventional oven, increase the temperature by 10-20 degrees celsius.
Caramel layer - use full fat condensed milk not skim condensed milk as it won't set properly. I find that brand name condensed milk (ie. Nestle) sets better than home brand condensed milk. Cook the caramel layer until it’s firm. If it’s not firm, your caramel slice will end up in a runny mess! Cook it on the stovetop or in the Thermomix until it’s obviously thickened and then pour into your slice tin.
If you find that your crumble is over-browning, simply add a sheet of foil loosely over the top and continue baking.
This crumble slice is delicious served cool, or warmed up with a scoop of ice-cream, custard or cream.
Cut the slice using a sharp serrated knife.
Store the slice in an airtight container in the fridge for up to one week.
Freeze the slice in an airtight container for up to 3 months. Allow to defrost in the fridge before consuming.

A close up of oaty caramel crumble squares.

FAQs

Looks fancy? Tastes dangerously delicious.....

Can I replace rolled oats with quick oats?

I prefer to use plain rolled oats (also known as old fashioned oats) rather than quick oats, as I find they give the crumble a much nicer texture and crunch, however you can substitute with quick oats, if that's what you have on hand.

How do I ensure caramel crumble bars hold together when cut?

Firstly, when you sprinkle the remaining crumble over top of the caramel, lightly press the crumbs on to the caramel layer.
Secondly, keep the slice stored in an airtight container the fridge as this helps the caramel layer to set firmer than at room temperature.
And thirdly, use a sharp serrated knife to cut the slice.

Serving suggestions

The wonderful thing I love about this caramel oat slice (apart from the fact that it's absolutely delicious) is that it can be served warmed or cool.
Great with a cuppa, preferably served straight from the fridge.
If serving warm, add a scoop of vanilla ice cream, or a dollop of thickened or whipped cream, or you can drizzle with custard for the ultimate divine dessert.