01 -
Line a 9x13-inch pan with aluminum foil and lightly butter the foil. Set aside.
02 -
Melt butter in a large light-colored pot over medium heat, stirring constantly until golden brown and aromatic, about 5-8 minutes, then immediately remove from heat.
03 -
Add 4 cups marshmallows to browned butter and stir to combine. Return pot to low heat and continue stirring until marshmallows are fully melted.
04 -
Stir in salt and vanilla extract until evenly incorporated.
05 -
Add Rice Krispies cereal gradually, stirring quickly to coat evenly before mixture begins to cool.
06 -
Fold in reserved mini marshmallows and allow them to melt slightly, maintaining a smooth mixture.
07 -
Transfer mixture to prepared pan and gently press into an even layer using a buttered spatula or butter wrapper.
08 -
Allow to set at room temperature for approximately one hour before lifting out and cutting into bars.