These apple oat crumble bars have a buttery sweet oatmeal shortbread-like base topped with an apple pie filling, then another layer of oat crumble + walnuts and finally finished with a drizzle of homemade salted caramel sauce. Salted caramel and apple pie filling is a match made in heaven. These crispy oat crumble bars are the perfect way to enjoy this combo! You'll surely fall in love with these crisp, sweet and crunchy bars of goodness!

You can enjoy these bars for breakfast, as an afternoon snack or as a delicious dessert. They are easy and quick to make, and they will satisfy all of your oatmeal cravings!

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WHY YOU’LL LOVE THIS RECIPE!

• Easy to make! This recipe is so simple and ideal for beginners in baking. No electric mixer is required and you can make them by using simple and few ingredients that you probably already have on hand.
• Full of Nutrition! You can enjoy this yummy treat with lots of added nutrients. These bars are packed with oatmeal, homemade apple filling and walnuts.
• The recipe is versatile and easy to customise! You can use any nut or seed of your choice instead of walnuts like almonds or pumpkin seeds, pecans, or cashews.

INGREDIENTS YOU'LL NEED!

FOR APPLE FILLING

• Granny Smith apples (green 🍏): I used Granny Smith apples because they are hard, high in acid and lean in sugar. High-acid apples retain more flavour when cooked or baked. I love the tartness and sweetness of green apples. But you can use any kind of apples, like Golden Delicious or a mixture of multiple types of apples. 
• Salt: It is used to balance tartness and sweetness.
• Light Brown sugar: I used light brown sugar for a more rich and deeper flavour. It also gives caramelised flavour. You can use dark brown sugar instead.
• Lemon juice: It adds flavour and acidity to the apple filling. It helps to preserve the colour of apples and prevents the apples from turning brown by slowing down the oxidation process.
• Cornflour/Cornstarch: It is added to make the apple filling thick.
• Ground Cinnamon: Autumn/Fall baking is incomplete without cinnamon. It gives an amazing flavour to this apple filling.
• Unsalted butter: It will give flavour and shine to the apple filling and also helps it to thicken up. Always use unsalted butter, so you can control the amount of salt according to the recipe requirement. 

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FOR HOMEMADE SALTED CARAMEL SAUCE

• Granulated sugar: When sugar caramelises, it gives signature colour and flavour to the caramel sauce.
• Double Cream/Heavy cream: Cream keeps the caramel silky and smooth. Always use warm cream because cold cream causes the hot sugar to clump.
• Unsalted butter: Butter makes sauce rich, creamy and flavourful. Always use good quality butter. Always use room temperature butter as cold butter can seize the hot melted sugar.
• Salt: Salt balances the sweetness because this caramel sauce is very sweet.
• Vanilla extract: Add flavour to the caramel sauce but it’s optional.

FOR OAT CRUMBLE MIXTURE

• Plain Flour/All-purpose flour: Make sure to measure it correctly. The best way to measure all-purpose flour is by using a digital scale. If you don’t have then spoon the flour into the measuring cup and then scrape a knife across the top of the measuring cup to level the flour.
• Jumbo Rolled oats: Jumbo Rolled oats are the best for this recipe as they are thicker and give a chewy texture to these bars and they can hold their shape perfectly. You will feel the crunchiness and taste of oats in each bite. Don’t use instant oats.
• Vanilla extract: Adds flavour. Always use good quality vanilla extract.
• Light brown sugar: I used light brown sugar for a more rich and deeper flavour. It also gives caramelised flavour. You can use granulated sugar instead but brown sugar crust goes very well with apple filling and caramel.
• Salt: It balances the sweetness and enhances the flavours.
• Baking Soda: It is added to make crumble soft from the inside and crispy from the outside once baked.

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EQUIPMENT REQUIRED

• 9x9 inch baking pan
• Heavy-bottomed saucepan
• Heatproof spatula or wooden spoon
• Hand Whisk

HOW TO MAKE THESE BARS STEP BY STEP!

STEP 1: APPLE FILLING

• First wash, peel and core the apples and cut them into bite-sized chunks. Place them in a large pot and toss with lemon juice then add salt, light brown sugar, and butter. Cook over medium heat, for 10-15 minutes, uncovered, until the apples are soft, stirring occasionally.
• Whisk the 1 tbsp cornstarch and 3 tbsp water together until all the cornstarch has dissolved. Add into it and cook for a minute. Remove from the heat and let it cool to room temperature.

STEP 2: SALTED CARAMEL SAUCE

You can make caramel sauce by using two methods. Wet method and Dry method.      

In the wet method, sugar is combined with water in a pan. It's a slower method, because the more water you add, the longer the caramel will take since the water needs to evaporate before the sugar caramelises. I have a complete blog post on making salted caramel sauce with all tips & tricks by the wet method. You can find it here.

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In the dry method, only sugar is melted over low heat and there are fewer chances of crystallisation but sugar is more prone to burning so you have to keep an eye on it.

Both methods produce the perfect results so you should choose whichever one you prefer. Here, I'm going to show you how to make caramel using the dry method. Many people have trouble making caramel with the wet method because they're afraid that their caramel will crystallise, so if you are scared of that, this method is for you.

DRY METHOD

• Heat the double cream/heavy cream in the microwave and set aside. Prepare all your ingredients in advance so they are ready to add to the caramel when needed.
• Add the sugar into a light-coloured, heavy-bottomed saucepan. Spread it evenly and let it melt over low heat and wait for the sugar to melt (no stirring at this point, just swirl the pan).
• Once the sugar starts to melt and clump together, use a heatproof spatula or wooden spoon to stir it continuously until completely melted otherwise it can burn. Sugar makes clumps as it melts so no need to worry as it will gradually melt. Gently break up clumps using a spatula.
• Once the sugar has melted, stop stirring and swirl until a golden amber colour is achieved. Keep an eye on it as it takes only a few seconds to burn. Don’t let it get too dark as it makes the caramel bitter (the approximate time for the above entire process is 13-15 minutes).
• Remove from the heat and add in softened butter while constantly whisking. Mix until it is thoroughly combined. Whisk carefully as the mixture will bubble up and can splutter, add cream in two batches and stir until smooth.
• Add in salt and vanilla extract and stir until smooth. Put it back on low heat for 30 seconds. keep stirring until caramel is smooth.
• Pass this mixture through a strainer to remove any lumps of sugar. In this way, you can get silky and smooth caramel.
• Caramel sauce will be liquid when it is hot and will thicken up as it cools. Allow it to cool then transfer to an air-tight container. Store for up to 1 month in the fridge.
• It solidifies in the fridge. Reheat it in the microwave for a few seconds when needed.

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STEP 3: OAT CRUMBLE MIXTURE FOR THE BASE AND CRUMBLE TOPPING

• Grease a 9x9 inch square pan with butter, line with parchment paper leaving it to overhang on all sides. It’s important because it is easy to remove these bars from the pan. Lightly grease the parchment paper with butter, and set it aside. Preheat the Fan oven to 155C/311F (for conventional oven 175C/347F).
• In a large bowl, combine plain flour/all-purpose flour, light brown sugar, baking soda, salt and jumbo rolled oats.
• Add the cold cubed butter + vanilla extract. Rub the mixture and butter together between your fingertips until the mixture is crumbly but starts to stick together. If you squeeze the dough in a fist, it should stick together but easily fall apart when you rub it between your fingers.
• Reserve 1 cup of oat crumble mixture and set aside.
• Pour the remaining oat crumble mixture into the prepared baking pan. Press down the mixture firmly to form the crust, using your fingers to make an even layer. Use the base of a glass to make a perfectly flat base.

STEP 4: ASSEMBLY AND BAKING

• Pour the apple filling over the oat crumble base and level it off using the back of the spoon.
• Spread the 1 cup crumble mixture on top of the apple filling.
• Sprinkle the roughly chopped walnuts over the top (it’s optional).
• Pop the baking pan into the oven and bake for 40-45 minutes or until the top is golden brown and puffed in the middle and the apple filling is bubbling away.
• Leave the bars in the pan for 30 minutes to cool completely at room temperature then pop them in the fridge for more than 30 minutes before slicing.
• Use the parchment paper overhang to lift out the bars and place them over the cutting board. Make 16 squares, using a sharp knife.
• Before serving, drizzle the salted caramel sauce over the bars. If it has cooled too much reheat it again for a few seconds.

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PRO TIPS TO MAKE PERFECT CRUMBLY BARS!

• Always use good quality butter. Make sure to buy unsalted butter because you can control the amount of salt according to the recipe requirement. 
• Use Granny smith apples as they are the best apples for baking and cooking recipes. They are hard and firm and keep their shape beautifully when baked. They are more acidic and lean in sugar so they balance the sweetness in desserts.
• Always line your baking pan, leaving the overhang for easy removal.
• Use the back of a glass to flatten the oat crumble base as it will give a neat finish.
• Allow it to cool completely before slicing.
• Use a sharp knife and clean it before each cut.
• Drizzle warm caramel sauce just before serving otherwise bars will get soggy.

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HOW TO STORE THESE BARS?

Store the bars in the fridge in an airtight container for up to 4-5 days or freeze for up to 1 month. 

TO FREEZE THEM, Wrap each square in parchment paper and plastic wrap then keep them in a ziplock bag or freezer-safe container and freeze for up to 1-2 months. Thaw on the kitchen counter at room temperature and again bake in the preheated oven just for 5 minutes before using. Drizzle caramel sauce and enjoy.

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FAQ

Can I use a baking pan of different size?

If you don’t have a 9x9 inch baking pan, you can use an 8x8 inch pan but adjust the baking time accordingly as it will make thicker bars.

Do I use instant oats or quick oats?

Quick oats are not suitable for this recipe as they will change the consistency and texture of the bars.

Can I use store-bought caramel sauce?

Homemade caramel sauce is the best but if you’re in a hurry, you can use store-bought caramel sauce. You'll need 1/4 cup of store-bought caramel sauce.

I hope that you'll try this recipe and you'll love them as much as my family and I do! If you make this recipe then be sure to tag @kaotickrunch on Instagram. We'd love to see your creations!

Happy baking! 😊