01 - Set oven to 350°F. Line a 9x9-inch baking pan with parchment paper, allowing some excess paper to hang over the sides for easy removal.
02 - Combine flour, granulated sugar, brown sugar, cinnamon, and salt in a small bowl. Stir in melted butter until clumps form; set aside.
03 - Whisk together melted butter and brown sugar in a large mixing bowl until fully blended. Add eggs and vanilla extract, whisking until smooth.
04 - In a separate bowl, whisk flour, baking powder, salt, and cinnamon. Add the dry mixture to the wet ingredients and stir just until combined.
05 - Gently fold in diced apples until evenly distributed throughout the batter.
06 - Spread half the blondie batter into the prepared pan. Drizzle with half the caramel sauce. Add the remaining batter, top with the rest of the caramel sauce, and swirl lightly with a knife.
07 - Evenly distribute the reserved cinnamon crunch topping over the surface.
08 - Bake for 33 to 37 minutes, or until the center feels set and a toothpick inserted comes out with a few moist crumbs attached.
09 - Cool completely in the pan. Lift out using the parchment overhang and cut into squares. Drizzle with extra caramel sauce prior to serving, if desired.