Preheat 350F/180C and line an 8"X8" pan with foil, so the foil hangs over the sides of the pan. Grease the pan and set aside.

In a large bowl combine the flour, salt, and sugar. Using clean hands rub in the cold butter. Rub together with your fingers or a pastry blender. Once combined press ⅔ of the mixture into prepared pan. Use your hands to press into an even layer. Bake for 12-15 minutes, until set and lightly golden brown. Prepare remaining parts while the crust bakes.

Add the oats, cinnamon, cloves, and all spice to the remaining shortbread mixture. Use your hands to rub everything together. Place the bowl into the fridge while you prepare the filling.

In a large bowl place sliced apples, flour, brown sugar, and spices together. Place in the fridge while the crust finishes baking.

When the crust is baked let it cool for 5 minutes then place sliced apples in an even layer on top of the crust then sprinkle the crumble on top. Bake for 30-35 minutes, the top should be golden brown and the apples bubbling. The internal temperature should be 175F/80C.

Let the bars cool in the pan on the counter for 30 minutes then in the fridge for two hours. They need ample time to cool so that the apple filling sets up properly.

When ready to serve drizzle salted caramel all over the top. Store any leftovers in an air-tight container in the fridge for up to 5 days.