Prepare the 3 oz bag of microwave butter popcorn according to package directions. Transfer the popped corn to a large bowl and remove any unpopped kernels.

Add 1 cup tiny pretzel twists to the bowl with the popcorn and toss to combine.

In a small microwave-safe bowl, combine 1/4 cup creamy peanut butter and 2 tbsp butter. Microwave on HIGH for 1 to 1-1/2 minutes or until melted; stir until smooth.

Drizzle the melted peanut butter mixture evenly over the popcorn–pretzel mixture. Gently toss or stir to coat as evenly as possible.

Sprinkle 3/4 cup powdered (confectioners') sugar over the coated mixture and toss to coat. If you want a heavier coating, add up to 1 cup total powdered sugar, a little at a time, tossing after each addition until you reach the desired coating.

Add 1 cup peanut butter M&M's and gently fold or toss just until they are evenly distributed.

Let the mixture cool about 10 minutes so the coating firms, then serve. Store any leftovers in a tightly sealed container.