Preheat the oven to 350 degrees.
Line a 9 x 13 baking dish with foil. Spray the foil with cooking spray. Set aside.
In a large bowl combine the brown sugar, butter, applesauce, eggs, and vanilla.
In a medium bowl combine the flour, baking powder, salt, and cinnamon.
Add the flour mixture to the butter mixture and stir to combine.
Fold in the apples and pecans.
Pour the batter the prepared baking dish. Bake for 40-50 minutes or until a toothpick inserted into the center comes out clean.
Remove from oven and cool completely on a wire rack.
To prepare the frosting heat the brown sugar, butter, and milk in a heavy saucepan. Whisk continuously until the mixture boils. Boil one minute.
Remove from heat and add in the vanilla and powdered sugar. Whisk until smooth.
Place the frosting in the refrigerator for 5-10 minutes or until it thickens up.
Pour the frosting over the blondies. Quickly sprinkle with pecans.
Wait until the frosting hardens. Cut into 24 squares.