Step 1

Lightly grease a 9 × 13-inch pan and set it aside. In a large pot over low heat, stir the butter until melted. Continue stirring frequently. It will begin to sizzle and foam slightly before little golden bits start forming on the bottom of the pan. Continue stirring until the butter has browned. You’ll know it’s done when there are golden flecks throughout the butter and you notice a sweet, nutty fragrance. Immediately remove it from the heat and add the salt and vanilla, stirring carefully. Add all but 1 cup of the marshmallows and stir over low heat until they’re melted completely. Add the remaining marshmallows with the two cereals and stir just until combined.

Step 2

Turn the mixture out into the prepared pan and use the butter wrapper or a clean, lightly greased hand to pat the crispies flat in the pan. Allow them to cool completely before cutting and enjoying!