Preparation Steps

• Line a 9x9-inch baking pan with parchment, leaving an overhang on two sides for easy removal; lightly butter the parchment and set the pan aside. Measure the cereal into a large bowl so it's ready to add.
• In a large, heavy-bottomed saucepan over low heat, melt the butter, stirring occasionally until it just liquefies. Add about 7 cups of the mini marshmallows to the melted butter and stir constantly until the marshmallows are mostly melted and smooth, about 3–5 minutes.
• Remove the pan from the heat and immediately stir in the vanilla and the pinch of kosher salt. Pour the melted marshmallow mixture over the prepared cereal and, using a wide spatula, fold briefly to coat — work quickly so the marshmallow doesn’t set.
• Gently fold in the remaining 2 cups of mini marshmallows to give the bars extra chew and a fun texture contrast. Transfer the sticky mixture to the lined pan and press evenly using a piece of buttered parchment or a lightly greased spatula — press firmly but avoid compressing them too tightly (this keeps them airy).
• Let the pan sit at room temperature for about 25–35 minutes to set. For faster slicing, chill in the refrigerator for 10–15 minutes until just firm. Lift the slab from the pan using the parchment overhang and place on a cutting board.
• Using a sharp knife lightly greased or a pizza cutter, score into 16 squares. Serve at room temperature. Store leftovers in an airtight container at room temp for up to 3 days or refrigerate to keep firmer longer.