Shortbread:

• 1 cup (2 sticks) unsalted butter, room temperature
• ½ cup (100g) granulated sugar
• ¼ cup (40g) brown sugar, lightly packed
• 1 tsp pure vanilla extract
• 2 cups (280g) all-purpose flour
• ¾ tsp kosher salt
• 1 tsp cinnamon
• ½ tsp ginger
• ½ tsp nutmeg
• ½ tsp all-spice

‍

Apple Filling:

• 4 apples, peeled, cored and sliced
• 1 tbsp lemon juice (1 lemon)
• 3 tbsp granulated sugar
• 1 tsp cinnamon
• 2 tbsp unsalted butter
• 1 tsp cornstarch
• ¼ cup salted caramel sauce

‍

Streusel:

• ½ cup (50g) old-fashioned whole rolled oats
• ⅓ cup (50g) brown sugar
• ¼ cup (½ stick) unsalted butter, cold and cubed
• ½ tsp cinnamon
• ¼ cup (35g) all-purpose flour

‍

Glaze:

• 2 tbsp unsalted butter, melted
• 1 cup (110g) powdered sugar
• 1 tbsp whole milk
• 1 tsp pure vanilla extract

1. Preheat the oven to 375°F.
2. Butter an 8 X 8 inch pan and line it with parchment paper.  Set aside.
3. Shortbread: Cream the softened butter, granulated sugar and brown sugar with a wooden spoon in a large bowl.  Alternatively, you can use a stand mixer fitted with a paddle attachment.
4. Stir in the vanilla until combined.
5. Whisk the flour, salt, cinnamon, ginger, nutmeg and all-spice together in a small bowl until combined.
6. Fold the dry ingredients into the dough.
7. Press the dough evenly into the prepared pan.
8. Bake the shortbread for 23 minutes, until it is golden brown. 
9. Set the pan on a wire rack and let the shortbread cool completely.
10. Apple Filling: Place the peeled, cored and sliced apples in a large bowl.
11. Pour the lemon juice over the apples.
12. Sprinkle the granulated sugar and cinnamon over the apples.
13. Toss the apples until they are well coated.
14. Melt the butter in a large frying pan.
15. Pour the apples into the frying pan and cook for 10 to 12 minutes, until the apples are tender and some of the liquid evaporated.
16. Stir in the cornstarch and keep cooking the apples for 1 more minute.
17. Pour the apples over the shortbread and spread into an even layer.
18. Use a small offset spatula (or spoon) to spread the salted caramel sauce over the apples.
19. Streusel: Mix the oats, butter, brown sugar, flour and cinnamon together in a small bowl.
20. Spread the chunks of streusel over the caramel layer.
21. Bake for 25 minutes, until the streusel is golden brown.
22. Let cool completely.
23. Glaze: Mix the melted butter, powdered sugar, milk and vanilla together in a small bowl.
24. Use a spoon to drop dollops of the glaze over the streusel.
25. Remove the shortbread from the pan.
26. Slice into 9 bars.
27. Store in an airtight container in the fridge for up to 3 days.