Salted Caramel Apple Oat Crumble Bars

FOR APPLE FILLING

• 6 medium Granny Smith Apple (green 🍏)
• 1/4 tsp salt
• 1 tbsp lemon juice
• 1/3 cup (75 g) Light brown sugar packed
• 2 tbsp (28 g) unsalted butter
• 1/2 tsp ground cinnamon 
• 1 tbsp Corn flour/Corn starch dissolved in 3 tbsp of water

FOR SALTED CARAMEL SAUCE

• 100 g (1/2 cup) granulated sugar
• 28 g (2 tbsp) unsalted butter, softened to room temperature 
• 1/4 tsp sea salt/or table salt
• 100 ml (approx. 1/3 cup + 1 tbsp) double cream/heavy cream (warm)
• 1/2 tsp vanilla extract

FOR OAT CRUMBLE MIXTURE

• 173 g (1 1/3 cup) Plain flour/all-purpose flour 
• 142 g (1 1/2 cup) Jumbo rolled oats
• 1/4 tsp salt
• 1/2 tsp baking soda
• 125 g (1/2 cup + 2 tbsp) Light brown sugar
• 140 g (1/2 cup + 2 tbsp) unsalted butter
• 1/2 tsp vanilla extract 
• 2-3 tbsp roughly chopped Walnuts for the top

APPLE FILLING

1. 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.
2. 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.

SALTED CARAMEL SAUCE

1. 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.
2. 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).
3. 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.
4. 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).
5. 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.
6. 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.
7. Pass this mixture through a strainer to remove any lumps of sugar. In this way, you can get silky and smooth caramel.
8. 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.
9. It solidifies in the fridge. Reheat it in the microwave for a few seconds when needed.

OAT CRUMBLE MIXTURE FOR THE BASE AND CRUMBLE TOPPING

1. 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).
2. In a large bowl, combine plain flour/all-purpose flour, light brown sugar, baking soda, salt and jumbo rolled oats.
3. 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.
4. Reserve 1 cup of oat crumble mixture and set aside.
5. 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.

ASSEMBLY AND BAKING

1. Pour the apple filling over the oat crumble base and level it off using the back of the spoon.
2. Spread the 1 cup crumble mixture on top of the apple filling.
3. Sprinkle the roughly chopped walnuts over the top (it’s optional).
4. 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.
5. 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.
6. Use the parchment paper overhang to lift out the bars and place them over the cutting board. Make 16 squares, using a sharp knife.
7. Before serving, drizzle the salted caramel sauce over the bars. If it has cooled too much reheat it again for a few seconds. Enjoy 😊 

NOTES

1. Store the bars in the fridge in an airtight container for up to 4-5 days or freeze for up to 1 month.
2. 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.