Preheat oven to 350°F/177°C. Line a 9" x13" baking pan with parchment paper. Set aside.
Apple Filling
In a medium mixing bowl combine apple ingredients together, light brown sugar, pure vanilla extract, ground cinnamon, chopped apples, and chopped pecans. Set aside.
Prepare the batter
In a medium size mixing bowl, whisk the dry ingredients, all-purpose flour, baking powder, salt, and cinnamon. Set aside.
Use a stand mixer with paddles attached or a large mixing bowl with an electric hand mixer with beaters attached, cream together, unsalted butter, brown sugar, white sugar, eggs, and vanilla until well combined, about 5 minutes.
Gradually beat in the dry ingredients until a batter forms.
Fold in the apple mixture to combine the ingredients.
Spread the batter into the prepared baking dish and bake in the preheated oven for 25-30 minutes or until a toothpick comes out clean.
Allow the blondies to cool slightly while making the glaze.
Whiskey Glaze
In a medium bowl, whisk all the glaze ingredients together, the confectioner's sugar, whiskey, milk, and white sugar until combined and smooth. Spread evenly over the blondies and allow the glaze to harden.
Slice and enjoy on their own or top with your favorite ice cream and whipped cream.
Notes
Note 1: Use a good baking apple such as Gala, Braeburn, Honeycrisp, or Golden Delicious are a few tasty options. Note 2: For the whiskey, any of your favorites can be used such as Jameson, Makers Mark, or even Cinnamon Whiskey. If a non-alcoholic glaze is preferred, use 1 teaspoon of pure vanilla extract or rum extract.