Preheat your oven to 350°F (175°C). This ensures that your blondies bake evenly.
Line a 9x13 inch baking pan with parchment paper, leaving some overhang for easy removal later. Lightly grease the parchment for added non-stick assurance.
In a large mixing bowl, cream together the softened butter and brown sugar using a whisk or electric mixer until the mixture is light and fluffy.
Add the eggs and vanilla extract to the butter and sugar mixture. Beat until fully combined and smooth.
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 coarsely chopped Nutter Butter cookies. Be careful not to overmix.
Pour the blondie batter into the prepared baking pan and spread it evenly using a spatula. Sprinkle the remaining peanut butter chips on top, followed by a handful of sprinkles for an extra festive touch.
Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. Avoid overbaking to keep the blondies soft and chewy.
Once baked, remove the pan from the oven and allow the blondies to cool in the pan for about 10 minutes. Use the parchment overhang to lift the blondies out of the pan and onto a cutting board. Let them cool completely before slicing into squares.