Mya Allen

Butter a 9x13-inch baking pan and line with parchment paper.
Melt butter in a large pot or dutch oven over medium-low heat. Continue to cook the butter, swirling the pan occasionally. It should become foamy and begin to crack and pop audibly. When the crackling stops, continue to swirl the pan until the butter develops a nutty aroma and brown bits start to form at the bottom. Once the bits are amber in color, 2 to 3 minutes after the popping stops, add the salt, vanilla, and marshmallows (reserve about a cup of marshmallows). Reducing the heat to low, stir constantly until the marshmallows are completely melted. Remove from heat.
Add the rice Krispies cereal and reserved marshmallows and stir with a rubber spatula or until the cereal is evenly coated. Transfer the mixture into the prepared baking pan. Try to spread the mixture as opposed to pressing into the baking dish-this helps create a lighter, chewier, airier texture.
Allow to cool to room temperature, about 1 hour. Cut into squares before serving.