Preheat your oven to 350°F (175°C). This ensures your blondies bake evenly.
In a medium saucepan over low heat, melt the butter. Once melted, remove it from heat and let it cool slightly.
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 mixture to the wet ingredients, stirring until just combined.
Gently fold in the butterscotch chips, half of the peanut butter chips, and the coarsely chopped Nutter Butter cookies. Make sure everything is evenly distributed throughout the batter.
Line your 9x13 inch baking pan with parchment paper or grease it lightly with butter. This will help prevent sticking.
Pour the blondie batter into the prepared pan, spreading it evenly. Sprinkle the remaining peanut butter chips on top, and don’t forget to add a handful of colorful sprinkles for that 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.
Once baked, remove the blondies from the oven and allow them to cool in the pan for about 10 minutes. Then, transfer them to a wire rack to cool completely before cutting into squares.