Prepare the Cereal
Add cereal to a large mixing bowl.
Make sure the bowl is large enough for tossing without crushing the cereal.
Melt the Chocolate
Melt white chocolate in the microwave in 20–30 second intervals, stirring between each.
Add butter or coconut oil if using, and stir until smooth.
Stir in vanilla extract if desired.
Coat the Cereal
Pour melted chocolate over the cereal.
Gently fold with a spatula until evenly coated.
Add Powdered Sugar
Transfer coated cereal to a large zip-top bag or bowl with lid.
Add powdered sugar.
Shake gently until all pieces are coated.
Add Valentine Mix-Ins
Spread puppy chow on parchment paper to cool.
Once set, gently mix in Valentine candies, sprinkles, and marshmallows.
Serve or Package
Serve immediately or package into treat bags, jars, or boxes for gifting.