Preheat the oven to 350°F and line an 8x8 inch pan with parchment paper.
Brown the butter & let it cool:In a small saucepan, cook the butter over low-medium heat while stirring consistently. Once it starts to turn brown on the bottom and give off a nutty scent, remove it from the heat. Transfer it to a large heat-resistant bowl & let it cool.
When the brown butter is warm to touch, mix in the sugars. Stir in the cookie butter, egg and vanilla extract, mixing well after each addition.
In a small bowl, whisk together the flour, baking powder and salt. Then, stir them into the wet ingredients until there are barely any flour streaks visible.
Mix in the chocolate and butterscotch chips. Spread the batter out evenly in the prepared pan. Bake for 20-30 minutes.*
Let the bars cool in the pan before you remove them. Slice into 9 or 16 squares and enjoy!
Notes
*Bake for less time for gooey blondies or more time for more firm blondies.Store in an airtight container at room temperature for 1 week or in the freezer for up to 1 month.The provided nutrition information is an estimate, the calorie accuracy is not guaranteed.