Ingredients:

  • 2 cups All-Purpose Flour (for crust)
  • 1/2 cup Granulated Sugar (for crust)
  • 1/2 tsp Salt (for crust)
  • 1 cup Unsalted Butter, very cold, cut into 1/2 inch cubes (for crust)
  • 1 large Egg Yolk
  • 6 medium Baking Apples (approx. 1 kg), peeled, cored, and sliced 1/4 inch thick
  • 1/4 cup packed Brown Sugar (for filling)
  • 2 Tbsp Cornstarch (or Plain Flour)
  • 1 Tbsp Lemon Juice (freshly squeezed)
  • 1 tsp Ground Cinnamon (for filling)
  • 1/4 tsp Ground Nutmeg
  • 1 cup All-Purpose Flour (for streusel)
  • 1/2 cup Rolled Oats (not instant)
  • 1/2 cup packed Brown Sugar (for streusel)
  • 1/2 tsp Ground Cinnamon (for streusel)
  • Pinch Salt (for streusel)
  • 1/2 cup Unsalted Butter, very cold, cut into small cubes (for streusel)

Instructions:

  1. Stage 1: Prepare the Streusel. In a medium bowl, whisk together the flour, oats, brown sugar, cinnamon, and salt for the streusel.
  2. Add the cold, cubed streusel butter. Use a pastry blender or your fingertips to cut the butter into the dry mixture until large, pea-sized crumbs form.
  3. Chill: Place the streusel mixture in the refrigerator while preparing the rest of the recipe.
  4. Stage 2: Make and Pre-Bake the Crust. Preheat oven to 350°F (175°C). Line the 9x13 inch pan with parchment paper, allowing an overhang on the long sides for easy removal.
  5. In a large bowl, whisk the crust flour, sugar, and salt.
  6. Incorporate Butter: Cut in the cold crust butter using a pastry blender or pulse in a food processor until the mixture resembles coarse sand.
  7. Bind: Add the single egg yolk and mix until the dough just comes together into moist clumps. Do not overmix.
  8. Press and Chill: Press the dough evenly into the bottom of the prepared pan. Prick the base all over with a fork. Chill the crust for 30 minutes.
  9. Par-Bake: Bake the chilled crust for 15 minutes until lightly set and barely beginning to turn golden around the edges. Remove and set aside.
  10. Stage 3: Prepare the Filling and Assemble. In a large bowl, toss the sliced apples with brown sugar, cornstarch (or flour), lemon juice, cinnamon, and nutmeg until the slices are evenly coated.
  11. Layer Filling: Pour the apple mixture evenly over the warm, par-baked crust.
  12. Add Topping: Distribute the chilled streusel topping evenly over the apples.
  13. Stage 4: Final Bake and Cooling. Return the pan to the oven and bake for 30–35 minutes, or until the streusel is golden brown and the filling is bubbling thickly (the apples should yield slightly when pierced with a knife).
  14. Cool Completely: Allow the bars to cool in the pan on a wire rack for a minimum of 2 hours, or ideally, chill them completely in the fridge before attempting to slice.
  15. Slice and Serve: Once firm, lift the bars out using the parchment overhang and cut into 12 squares.