1. Preheat oven to 350. Line a 9x13 pan with parchment paper.
2. Cut butter into tablespoon-sized pieces and melt over medium heat. Once the butter has fully melted, begin to stir as it foams. Keep stirring until butter becomes a caramel-like color and dark bits start to form at the bottom of pan. Pull the butter once browned and immediately transfer to a large bowl. Transfer two tablespoons into a small bowl to use for the glaze later. Let butter cool while you prepare apples.
3. Add chopped apples to the same pan you browned the butter in, along with maple syrup. Cook over medium heat for 3-4 minutes until apples soften. Remove from heat.
4. Add brown sugar, eggs, vanilla, spices and salt to butter and whisk to combine. Add baking powder and whisk again really well to make sure it's fully mixed in.
5. Fold in flour until just combined, and then fold in apples.
6. Spread into pan and bake for 30-35 minutes, or until edges are set but middle is still a little bit gooey. Let blondies cool completely before glazing.

Make glaze:

1. Whisk together reserved butter (stick in the microwave if it's solidified - which it probably will be), bourbon, milk and vanilla until combined. Whisk in powdered sugar and mix until smooth. If the glaze feels too thick, add more milk a teaspoon at a time until you get your desired consistency.
2. Drizzle glaze on cooled blondies.

Recipe from Sally's Baking Addiction.