Preheat your oven to 350°F (175°C) and line an 11×7-inch pan with tin foil or spray with cooking spray.
Prepare the Apple Filling:
In a skillet over medium-low heat, cook the apples, brown sugar, butter, vanilla extract, and cinnamon for about 3-4 minutes until the apples are soft. Remove from heat and let cool.
Prepare the Blondies:
In a large bowl, cream the softened butter until light and fluffy, about 1 minute.
Add in the brown sugar and granulated sugar and mix until well combined.
Add in the eggs one at a time, beating well after each addition.
Mix in the vanilla extract and salt.
In a separate bowl, whisk together the flour, baking powder, and cinnamon. Gradually add the dry ingredients to the wet mixture, stirring until combined. The batter will be thick.
Assemble:
Spread half of the blondie batter evenly in the prepared pan.
Layer the cooled apple filling over the blondie batter.
Top with the remaining blondie batter and spread it evenly.
Bake in the preheated oven for 25-30 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean. Let the blondies cool completely before adding the glaze.
Prepare the Maple Glaze:
In a small saucepan, melt the butter over medium heat.
Add the maple syrup and bring to a gentle boil.
Remove from heat and whisk in the powdered sugar, vanilla extract, and cinnamon until smooth.
Drizzle the maple glaze over the cooled blondies, spreading evenly with a spatula if needed. Allow the glaze to set before cutting the blondies into squares.