Step 1: Prepare Apple Filling. In a medium skillet, combine finely chopped apples, brown sugar, butter, vanilla extract, and cinnamon. Cook over medium-low heat for about 3-4 minutes, until the apples soften and the mixture becomes fragrant and syrupy. Remove from heat and let cool.

Step 2: Prepare Blondie Batter. In a large mixing bowl, cream the softened butter for about 2 minutes. Gradually add both sugars, mixing well. Add the eggs one at a time, beating well. Stir in the salt and vanilla until fully incorporated.

Step 3: Combine Dry Ingredients. In another bowl, whisk together flour, baking powder, and cinnamon. Gradually add the dry mix to the wet ingredients, stirring gently until just combined.

Step 4: Layer Blondies. Preheat oven to 350°F (175°C) and grease an 11x7 inch baking pan. Spread half of the blondie batter into the pan. Spoon the cooled apple filling on top, then dollop remaining batter over it.

Step 5: Bake. Bake for 25-30 minutes until golden brown. A toothpick should come out clean. Allow to cool on a wire rack for about 10 minutes before glazing.

Step 6: Prepare Maple Glaze. Melt butter in a small saucepan. Whisk in the maple syrup, vanilla, and cinnamon. Gradually add powdered sugar, stirring until smooth. Let cool slightly.

Step 7: Glaze Blondies. Pour the maple glaze over the cooled blondies and let it set for a few minutes before slicing into squares.