# What you'll need:
→ Base Layer
01 - 2 cups all-purpose flour
02 - 1/2 cup granulated sugar
03 - 1/2 teaspoon baking powder
04 - 1/4 teaspoon salt
05 - 1/2 cup unsalted butter, cold and cubed
06 - 1 large egg, lightly beaten
→ Apple Filling
07 - 3 medium apples, peeled, cored, and diced
08 - 1/4 cup granulated sugar
09 - 1 teaspoon ground cinnamon
10 - 1 tablespoon lemon juice
11 - 1 tablespoon all-purpose flour
→ Crumble Topping
12 - 3/4 cup old-fashioned oats
13 - 1/2 cup all-purpose flour
14 - 1/3 cup brown sugar, packed
15 - 1/4 teaspoon ground cinnamon
16 - 1/4 teaspoon salt
17 - 1/2 cup unsalted butter, melted
# Method:
01 - Set oven to 350°F (177°C). Line a 9x9-inch baking pan with parchment paper, allowing for overhang.
02 - Combine flour, granulated sugar, baking powder, and salt in a mixing bowl. Cut in cold butter until mixture resembles coarse crumbs. Add egg and blend until just incorporated. Press evenly into prepared pan.
03 - Toss diced apples with granulated sugar, cinnamon, lemon juice, and flour until evenly coated. Spread the mixture over the base layer.
04 - Stir together oats, flour, brown sugar, cinnamon, and salt. Add melted butter, mixing until large clumps form. Distribute evenly over apple filling.
05 - Transfer pan to center rack and bake for 38–42 minutes, or until topping is golden and apples are tender.
06 - Allow bars to cool completely in pan before lifting and slicing. Serve at room temperature or gently warmed.
