Spray a 9x13-inch baking dish* with nonstick cooking spray.
In a large bowl, combine the fruity pebbles, rice krispies, and 2 cups of the marshmallows. Mix.
In a large saucepan, melt the butter. Add the remaining marshmallows and cook, stirring, until the butter is melted. Turn off the heat and stir in the vanilla and the salt.
Pour the melted marshmallow mix over the cereal and stir until fully combined.
Pour the mixture into the prepared baking dish. Lightly press the cereal into the dish.** You don’t want to compact the cereal down, just press down enough to make an even layer.
Let the bars cool to room temperature, then cut into bars to serve
Notes
You want to make sure your baking dish is at least 2 inches tall. These treats are tall!The easiest way to press the cereal into the baking dish is with buttered hands, or with a piece of wax paper.Nutrition information provided as an estimate only. Various brands and products can change the counts. Any nutritional information should be used as a general guide.