Preheat oven to 350°.
Using a hand mixer or stand mixer, mix butter, brown sugar, eggs, and vanilla until they are smooth and creamy.
Add the flour, baking powder, and salt.
Mix for 2-3 minutes, scraping down the sides of the bowl as needed.
Add chocolate chips or chocolate candies. (Save 1/2 cup of the candies for the top of the blondie.)
Spray a skillet with non-stick cooking spray. If you are using a well-seasoned cast-iron skillet, no need to spray it.
Scoop the blondie dough into the skillet and spread it out evenly to the edges.
Place the extra candies on the top of the blondie dough.
Bake at 350° for 40-45 minutes.