Preheat your oven: Start by preheating your oven to 350°F (175°C). Prepare a 9x13 inch baking dish by lining it with foil, leaving an overhang, and buttering or spraying it with non-stick spray for easy removal later on.
Combine wet ingredients: In a large mixing bowl, whisk together 2 Cups of firmly packed brown sugar with 1 Cup of melted and cooled unsalted butter, 2 large lightly beaten eggs, and 2 teaspoons of vanilla extract until the mixture is smooth and well combined.
Mix dry ingredients: In another bowl, whisk together 2 Cups of all-purpose flour, 2 teaspoons of baking powder, and 1/2 teaspoon of salt. Gradually add the dry mixture to the wet ingredients, stirring until just combined.
Add apples and pecans: Gently fold in 2 peeled, cored, and chopped Granny Smith apples and 1 Cup of chopped pecans into the batter until evenly distributed. Pour the batter into the prepared baking dish, spreading it evenly with a spatula.
Bake the blondies: Place the dish in the oven and bake for 40-50 minutes. Check for doneness by inserting a toothpick into the center; it should come out clean or with just a few moist crumbs attached. Once done, allow the blondies to cool completely in the pan.
Prepare the caramel glaze: In a saucepan over medium heat, combine 1/2 Cup of firmly packed brown sugar, 1/4 Cup of unsalted butter, and 3 tablespoons of milk. Bring the mixture to a boil, whisking constantly for about 1 minute. Remove from heat and stir in 1 teaspoon of vanilla extract and 1 Cup of powdered sugar until smooth.
Glaze the blondies: Once the blondies have cooled, drizzle the caramel glaze over the top. For added crunch and flavor, sprinkle with 1 Cup of chopped pecans.