Line a 9x13 baking dish with doubled aluminum foil and a few inch overhang on both ends. Butter or spray lined the dish with nonstick cooking spray. (I prefer using a metal rather than glass dish for this but use whichever you like)
In a large bowl, stir together brown sugar (2 cups), melted butter (1 cup), eggs (2), and vanilla (2 teaspoons).
In a separate bowl, stir together flour (2 cups), baking powder (2 teaspoons), and salt (1/2 teaspoon). Add to brown sugar mixture and stir until combined. Stir in apples (2) and pecans (1 cup). Pour batter into prepared baking dish.
Bake in preheated oven for 40-50 minutes or until a toothpick inserted in the center comes out clean. Cool completely.
Meanwhile, prepare glaze. In a heavy-bottomed 2-quart saucepan, bring brown sugar (1/2 cup), butter (1/4 cup), and milk (3 tablespoons) to a boil over medium heat. Boil 1 minute, whisking constantly. Remove from heat.
Add vanilla (1 teaspoon) and powdered sugar (1 cup), and using a hand-held electric mixer beat on medium speed until smooth. Pout immediately over cooled blondies and sprinkle with pecans (1 cup).
Notes
Cut cleanly: For neat slices, chill the bars briefly after glazing. The caramel will firm up, and your knife will glide right through.
Upgrade with sea salt: A sprinkle of flaky sea salt over the caramel glaze turns these into salted caramel apple brownies—absolutely divine!
Storage tip: These stay moist for days thanks to the apples and brown sugar—just cover tightly and keep at room temperature.
Perfect texture: The key is not to overbake. Pull them out when a toothpick comes out mostly clean; they’ll finish setting as they cool.