Line a baking sheet with parchment paper.
In a big microwave-safe bowl, melt the blue candy melts, peanut butter, and butter in 30-second bursts—stirring between each—until it’s all smooth and dreamy. Stir in the vanilla.
Toss in the Rice Chex and gently mix until every piece is coated.
Scoop half the cereal into a ziplock bag, pour in half the powdered sugar, seal it tight and shake, shake, shake!
Spread the coated cereal out on your parchment-lined tray. Repeat with the second half.
Once everything’s all sugared up and happy, dump it all back in your big bowl and gently fold in the crushed cookies.
Spread it back on the tray and let it set for about an hour. This helps it firm up a bit so it’s not just a crumbly mess.
Store it in an airtight container and add the candy eyeballs right before serving.