01 -
Line a 9 x 13-inch pan with heavy duty aluminum foil and lightly grease with softened butter. Set aside 2 cups of the marshmallows for later use.
02 -
In a large pot with light bottom, melt butter over medium heat, saving wrappers for later. Swirl pan occasionally until butter progresses from yellow to golden to toasty-brown with nutty aroma. Remove from heat when sediment forms (strain if too dark).
03 -
Off heat, add remaining marshmallows, vanilla, and salt to browned butter. Return to medium heat and stir with wooden spoon until marshmallows are completely melted and smooth.
04 -
Remove pan from heat and add Rice Krispies cereal. Using rubber spatula or wooden spoon, stir until evenly coated with marshmallow mixture.
05 -
Stir in reserved marshmallows until softened and partially melted. Avoid overmixing to maintain pockets of gooey texture.
06 -
Transfer mixture to prepared pan. Using saved butter wrappers or damp fingers, press gently into even layer. Cool at room temperature for at least one hour before cutting.
07 -
Use foil overhang to lift treats onto cutting board. Cut into squares with serrated bread knife. Store in airtight container at room temperature up to 5 days.