Initial Preparation: Preheat your oven to a temperature of 350°F. Prepare an 11x7-inch pan, either by lining it with tin foil or by administering a coat of cooking spray.
Apple Filling: Over a medium-low flame, sauté the diced apples with brown sugar, butter, vanilla extract, and cinnamon for approximately 3-4 minutes. Once done, set aside to cool.
Blondie Mixture: Commence by creaming the butter until its consistency becomes aerated. Incorporate both the granulated and brown sugar, ensuring a homogeneous blend. Introduce the eggs sequentially, ensuring each is thoroughly combined before adding the next. Subsequently, incorporate the salt and vanilla extract. In a separate vessel, amalgamate the flour, baking powder, and cinnamon. Gradually merge this dry mixture into the wet ingredients until a uniform batter is obtained.
Assembly: In the prepared pan, distribute half of the blondie batter, ensuring an even layer. Disperse the cooled apple filling atop this layer. Complete the assembly by spreading the remaining blondie batter over the apple filling, ensuring a level finish.
Baking: Place the pan in the preheated oven for a duration of 25-30 minutes, or until the surface acquires a golden-brown hue and a testing instrument emerges cleanly when inserted.
Maple Glaze Preparation: In a saucepan, combine the butter, maple syrup, vanilla extract, and cinnamon. Allow the mixture to melt over low heat. Once melted, remove from heat and methodically sift in the powdered sugar, whisking continually to ensure a smooth glaze. Allow the glaze to cool for approximately 8-10 minutes, permitting it to thicken slightly.
Finishing: After removing the blondies from the oven, allow them a cooling period of 10 minutes. Following this, uniformly pour the prepared maple glaze over the surface. Once the glaze has set, segment the dessert into individual squares for serving.