BROWN BUTTER: Melt butter in a medium skillet over low heat. Continue to swirl the pan as the butter bubbles until the butter turns a dark golden color and takes on a nutty caramel fragrance. Pour into a medium-sized bowl and set aside to cool.
PREP: Preheat the oven to 350°F and line a 9-inch square pan with aluminum foil or parchment paper.
DRY INGREDIENTS: In a medium bowl, whisk the flour, baking powder, and salt together and set aside.
WET INGREDIENTS: Add brown sugar to the bowl of melted butter and whisk together until combined. Then add the eggs and vanilla extract until combined.
COMBINE: Pour the dry ingredients into the wet ingredients and gently stir until just combined. Fold in the butterscotch chips and pecans. The batter will be thick.
BAKE: Spread batter into prepared pan in one even layer. Bake for about 35-40 minutes. Remove from the oven and allow the blondies to cool completely in the pan.
SERVE & STORE: Serve the blondies warm or at room temperature and keep in an airtight container in the fridge for up to 7 days.