Place the large pot over medium heat then brown your butter. The butter will be browned after it's melted, once you see brown bits on the bottom of the pan (this adds a rich, nutty flavor).
1/4 cup salted butter
Take the browned butter off the heat or transfer to a large bowl.
Add peanut butter and chocolate chips and stir until melted. Stir in vanilla.
1/2 cup creamy peanut butter, 1 cup semi-sweet chocolate chips, 1 teaspoon vanilla extract
Add rice squares cereal to the melted chocolate and carefully toss to evenly coat the cereal with the chocolate mixture. Let this mixture cool for a few minutes -- you can spread it out on a sheet pan for faster cooling if you'd like.
8 cups crispy rice squares cereal
Place the confectioners sugar in a gallon-sized bag. Add chocolate-coated cereal pieces to the bag, seal tightly, then gently toss and shake to evenly coat everything in the powdered sugar.
1 cup confectioners' sugar
You can add your mix-ins straight to the bag, but they'll also get a little coated in the powdered sugar. Alternatively, you can spread the powdered sugar-coated puppy chow on a sheet pan, add toppings, then gently toss to combine.
1/2 cup Reese's pieces, 1/4 cup Halloween sprinkles
Serve immediately, or store in an airtight container.