Preparation

Special equipment: candy thermometer

• Lightly grease a 9-by-13-inch baking dish.
• In a small saucepan over medium heat, whisk together the sugar, ½ cup cold water, corn syrup and salt. Once the sugar is dissolved, let sit undisturbed until the mixture reaches soft ball stage, 235 to 240 degrees, then remove from heat.
• Meanwhile, in a large, deep, heatproof bowl, sprinkle the gelatin over the remaining ½ cup cold water. Let stand until softened, about 1 minute, then beat 2 minutes at medium speed.
• Carefully pour the sugar mixture into the gelatin, avoiding the beaters and sides of the bowl. Beat on high speed until mixture increases in volume and turns into thick, white marshmallow, 5 to 8 minutes. Add the vanilla and beat for 1 minute.
• In a medium saucepan over medium heat, melt the butter, whisking frequently. The butter will foam, then subside. Watch carefully as browned specks begin to form at the bottom of the pan, so it doesn’t burn. When the specks are amber brown and the butter has a nutty aroma, 3 to 4 minutes, add the marshmallow and mix together. Remove from heat and stir in the crispy rice cereal 1 cup at a time, mixing thoroughly to ensure even coating. Press evenly into the prepared dish and allow to cool.