Always keep these bars at room temperature. Once they’ve set, cover in plastic wrap and leave at room temp. If you’ve already served the bars and have leftover slices, place them in an air-tight container at room temp. They’ll keep for up to 3 days (then the puppy chow starts to get a little stale).
Rice Chex are gluten free and most marshmallows are also gluten free.
To make just the puppy chow, toss the mixture in an additional 1 cup of powdered sugar.