Preheat the oven to 350 degrees F. Line an 8 x 8-inch baking dish with parchment. Set aside.

Shortbread Crust2. In a large bowl, add the melted unsalted butter, sugar, sourdough discard, vanilla extract and salt. Mix with a whisk until smooth.

113g (½ c) unsalted butter, melted, 38g (3 T) sugar, 50g (¼ c) discard, 4g (1 tsp) vanilla, 1g (¼ tsp) salt

Add the flour and mix with a rubber spatula until a dough forms.

175g (1 ¼ c) flour

Pinch off pieces of the dough and scatter them evenly in the prepared baking dish. With your fingers or the back of a measuring cup, press the dough to form a crust. Bake for 15 minutes, then remove from the oven.

Apple Filling5. While the shortbread bakes, prepare the apple filling and streusel topping.

Peel and slice the apple into ⅛th inch pieces and add them to a medium bowl. To the apples, add the sugar, flour, cinnamon and nutmeg. Mix with a rubber spatula until the apples are fully coated with the sugar mixture. Set aside.

300g (about 3 small apples), 38g (3 T) sugar, 27g (3 T) flour, 3g (1 ½ tsp) cinnamon, 1g (¼ tsp) nutmeg

Streusel Topping7. To a small bowl, add the old-fashioned oats, brown sugar, cinnamon, and salt. Whisk until evenly incorporated.

90g (¾ c) old-fashioned oats, 75g (⅓ c) brown sugar, 1g (¼ tsp) cinnamon, 3g (½ tsp) salt

Cube the cold butter and add to the oat mixture. Cut in the butter with a pastry cutter, two forks or even your fingers, until it looks like coarse crumbs. Store in the fridge until ready to use.

57g (4 T) unsalted butter, cold

Assemble & Bake9. Once the shortbread crust is out of the oven, evenly top the apple filling on the warm crust. Then sprinkle the streusel on top. Continue to bake for 35–40 minutes or until the apples are soft and tender. I like to use a toothpick to check.

Homemade Salted Caramel12. To a medium pot, add white sugar and heat to medium heat on the stovetop. Leave the sugar for a few minutes. Once the sugar starts to melt, continue to give it a stir. Typically, it will dissolve completely in about 8-10 minutes. Keep an eye on it, and be sure the sugar doesn’t burn.

200g (1 c) sugar

85g (6 T) unsalted butter, room temperature

120g (½ c) heavy cream, room temperature, 3g (½ tsp) salt