Preheat your oven to 350 degrees Fahrenheit.
Line an 11x7 inch pan with tin foil or spray it with cooking spray.
In a mixing bowl, combine the all-purpose flour, baking powder, salt, and cinnamon.
In another bowl, cream together the softened butter, sugar, and dark brown sugar until light and fluffy.
Add in the eggs one at a time along with vanilla extract. Mix until fully combined.
Gradually add your dry mixture into the wet mixture while stirring until just combined.
Gently fold in your finely chopped apples until evenly distributed throughout the batter.
Spread the batter evenly into your prepared pan and bake for approximately 25 minutes or until golden brown on top.
While they bake, melt butter in a small saucepan over low heat. Stir in brown sugar, vanilla extract, and cinnamon until smooth.
Once baked, remove your blondies from the oven and immediately pour the warm topping over them while still hot.
In another bowl, whisk together melted butter, maple syrup, powdered sugar, vanilla extract, and ground cinnamon until smooth.