Day 1: Prepare Dough and Crumble for Fermentation

Make the cookie dough:

• In a large bowl, cream together softened butter, powdered sugar, and brown sugar until light and fluffy.
• Add egg, vanilla extract, and almond extract (if using), mix well.
• Add sourdough starter and mix until combined.
• In a separate bowl, whisk together flour, baking powder, salt, and cream of tartar.
• Gradually add dry ingredients to wet ingredients, mixing until just combined.
• Dump out onto plastic wrap, wrap well and refrigerate for 8-24 hours.
• Make the fermented crumble:
• In a medium bowl, mix flour, brown sugar, salt, powdered sugar, cinnamon, nutmeg, ginger, and sourdough starter.
• Add cold cubed butter and cut in using a pastry cutter or your fingers until mixture resembles coarse crumbs.
• Add vanilla and mix gently.
• Cover and refrigerate alongside the cookie dough for 8-24 hours.

Day 2: Assembly and Baking

• Prepare the apple pie filling:
• In a medium saucepan, combine diced apples, brown sugar, lemon juice, vanilla extract, cinnamon, nutmeg, ginger, and salt.
• Add butter and cook over medium heat, stirring gently, for 5-8 minutes until apples begin to soften and release their juices.
• In a small bowl, whisk cornstarch with 2 tablespoons of water to create a slurry.
• Add the cornstarch slurry slowly to the apple mixture and stir gently to combine.
• Continue cooking for 3-5 more minutes until apples are tender but still hold their shape and mixture thickens significantly.
• The filling should be glossy and coat the back of a spoon, with most liquid absorbed and no raw cornstarch taste.
• Remove from heat and let cool completely (at least 45 minutes).
  

Prepare for assembly:

• Preheat oven to 350°F (175°C).
• Line a large baking sheet with parchment paper.
• Get your 2.5-3 inch circle cutter ready.

Assemble the cookies:

• Using your circle cutter as a guide, spread about 2 rounded tablespoons of fermented crumble mixture on the parchment in circles.
• For more apple pie filling to show through the finished cookies, spread your crumble in an irregular fashion with slight holes and gaps throughout the circle.
• Top each crumble circle with 1 rounded tablespoon of cooled apple pie filling, gently spread around the middle.
• Roll out the fermented cookie dough on a floured surface to a rough rectangle, 12″x 9″, approximately 3/8″ inch thick.
• Using your circle cutter, cut out circles from the dough.
• Gently gather scraps, press together to form a ball and roll out another rectangle, and continue cutting until all dough is used.
• Place each cookie circle on top of the crumble and apple layers.
• Gently press down to adhere making sure the crumble and apple filling are under the cookie.
  

Bake:

• Bake for 18-22 minutes, until you can see dark golden browning on the crumble edges around the bottom.
• Remove from oven and let cool completely on the baking sheet.

Make the homemade caramel:

• In a heavy-bottomed saucepan, combine sugar and water over medium heat.
• Swirl the pan gently (don’t stir with a spoon) until sugar dissolves and mixture begins to bubble.
• Once the sugar starts caramelizing, avoid stirring as this can cause crystallization. Gentle swirling keeps the mixture moving for even cooking.
• Continue cooking without stirring for 8-12 minutes until the mixture turns a deep amber color.
• Remove from heat immediately and carefully whisk in the warmed heavy cream (it will bubble vigorously).
• Add butter, salt, and vanilla extract, whisking until smooth.
• Let cool for 5-10 minutes until slightly thickened but still pourable.
  

Add caramel drizzle:

• While the caramel is still warm and pourable, use a spoon or piping bag to drizzle it over the cooled cookies.
• If the caramel has cooled too much and thickened, gently reheat it over low heat until pourable again.
• Allow to set for 30-45 minutes.