Lightly spray an 8×8-inch baking pan with nonstick cooking spray, then line it with parchment paper, leaving a little overhang on the sides for easy removal.
Add the butter to a large saucepan and melt over low heat. Keep the heat gentle to prevent the butter from browning or scorching.
Add the mini marshmallows to the melted butter. Stir continuously with a lightly greased spatula until the marshmallows are completely melted and smooth.
Remove the saucepan from the heat and quickly stir in the honey and vanilla extract until evenly incorporated. The honey adds a subtle sweetness that complements the flavor of the cereal.
Add the Honeycomb cereal and roasted salted peanuts to a large mixing bowl. Pour the warm marshmallow mixture over them and gently fold until the cereal is evenly coated. Work quickly because the marshmallow mixture begins to set as it cools.
Immediately transfer the mixture to the prepared baking pan. Lightly spray a piece of parchment or wax paper with nonstick spray and use it to gently press the cereal mixture into an even layer. Don't press too firmly or the treats can become overly dense.
Let the treats cool at room temperature for at least 1 hour, or until firm enough to cut cleanly. Lift them from the pan using the parchment overhang and cut into 12 squares with a lightly greased sharp knife.
