Preheat the oven to 350°. Line a 9x9-inch square baking dish with parchment paper and lightly spray with baking spray. Set aside.
In the bowl of a stand mixer fitted with a paddle combine butter, sugar and brown sugar. Beat on a medium speed until smooth. Add vanilla and mix to combine. Add flour and salt and mix until incorporated.
Press the dough evenly into the bottom of the prepared baking dish. Poke holes into the bottom of the crust, then place into the preheated oven on the center rack. Bake for 15 minutes, until lightly golden brown. Once baked, remove from the oven and place onto a wire cooling rack to cool.
For the Filling:
In a large mixing bowl combine sliced apples, sugar, cornstarch, brown sugar, cinnamon, nutmeg, salt and cloves. Mix until the apples are well coated.
Add in lime juice and mix to combine. Pour the apple mixture onto the pre-baked crust (it can still be warm).
For the Topping:
In a medium sized mixing bowl combine oats, flour, brown sugar, cinnamon and salt. Add butter and mix in using a fork until crumbly in texture. (hands work well too)
Spoon the topping mixture evenly over the apple filling. Place into the preheated oven on the center rack and bake for 55 minutes. Once baked, remove from the oven and place onto a wire cooling rack.
Allow to cool about 10-15 minutes before serving. Or serve chilled for a delicious twist.
Notes
STORAGE: Store apple pie bars in refrigerator for best flavor and texture for up to 3 days.
Freeze: Store in airtight container for up to 3 months. Thaw in refrigerator overnight.
For the cinnamon, nutmeg and cloves in the filling, you can swap out for 3 teaspoons apple pie spice.
Lemon juice can be used instead of lime, if desired.
APPLES- I suggest honeycrisp or granny smith (or a combination of both).
If mixture begins to burn or brown too quickly along the edges, loosely cover the pan with foil.