Spray a 9 x 13" baking pan with parchment paper. You can also line the pan with parchment paper for easier removal from the pan.
In a mixing bowl, beat butter until soft and creamy, 2-3 minutes. Add brown sugar and mix well, then stir in vanilla.
1 cup butter, 2 ¼ cups brown sugar, 1 tablespoon vanilla
Stir in eggs one at a time, mixing well after each egg.
3 eggs
Add flour to bowl and sprinkle baking powder and salt over the top of the flour. Mix well.
2 ½ cups flour, 2 teaspoons baking powder, ½ teaspoon salt
Measure out one cup of butterscotch chips and set aside. Add remaining butterscotch chips and chopped pecans to the mixing bowl. Use a large silicone spatula or spoon to fold everything together.
1 bag butterscotch chips, 1 cup pecans
Place in pan and spread so the batter is evenly distributed.
Sprinkle with the butterscotch chips you set aside.
Bake in preheated 350°F oven for 30-35 minutes until golden brown.
Remove from oven and let cool before slicing.
Notes
Make certain your butter is softened to room temperature before mixing.
Lining the pan with parchment paper makes it easier to lift the cooled brownies from the pan. You can also simply spray the pan with nonstick spray.
Avoid overbaking. The brownies should be golden brown when done.
Allow the brownies to cool before slicing.
Store cooled brownies in an airtight container at room temperature for 3–4 days.
To freeze, cool completely and slice into individual bars. Place in a freezer-safe container and freeze.