Spray a 9x-13-inch baking pan with non-stick spray or line with waxed paper, parchment paper, or aluminum foil (sprayed with non-stick spray.)
In a large heavy bottom pot (You'll need a soup pot or large Dutch oven) over medium-low heat, melt the butter.
Add the marshmallows and stir until they are almost completely melted. I like to leave some not completely melted. Stir in the vanilla.
Add the cereal and potato chips to the pot and stir well with a large spatula until the marshmallow and butter mixture covers all the cereal and chips.
Immediately pour and press into your prepared pan. Allow to cool before cutting.