Preheat your oven to 350°F (175°C).
Line a 9x13-inch baking pan with parchment paper.
In a large mixing bowl, whisk together the melted butter and brown sugar until well combined. Add in the eggs, one at a time, mixing well after each addition. Stir in the vanilla extract.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Gently fold in the butterscotch chips, half of the peanut butter chips, and the chopped Nutter Butter cookies.
Pour the blondie batter into the prepared baking pan and spread it out evenly. Sprinkle the remaining peanut butter chips on top and add colorful sprinkles.
Bake in the preheated oven for 25-30 minutes, or until the edges are golden brown and a toothpick inserted comes out with a few moist crumbs.
Allow the blondies to cool in the pan for 10-15 minutes before lifting them out using the parchment paper. Transfer to a wire rack to cool completely before cutting into squares.
