Grease a 9X13 pan with cooking spray or butter. You can also line your pan with parchment paper for the easiest removal.

In a large saucepan melt your butter over medium-low heat, stirring constantly until it turns a nice golden brown. This should take around 5 minutes, turn the stove off and leave butter in the saucepan.

Line two baking pans with parchment paper that has been sprayed with cooking spray or spread with butter, evenly spread one bag of mini marshmallows on each pan.

Place under broiler for 45 seconds to 1 minute or until marshmallows are puffed and golden brown. Watch them closely as they will go from golden brown to burnt quickly.

Spray a rubber spatula with cooking spray and use it to scrape the roasted marshmallows into the pan with the melted butter. Stir quickly to combine them well.

Pour the krispie cereal in and stir well, press evenly into prepared pan. Set aside and make marshmallow topping.

Combine egg whites and sugar in a pan or bowl placed over simmering water. Whisk constantly until mixture reaches 160 degrees F.

Transfer mixture to a stand mixer with the whisk attatchment, beat on medium high speed (speed 8 on a KitchenAid stand mixer) until the mixture doubles, cools and forms stiff peeks, this takes about 10-12 minutes.

Spread over Rice Krispie treats and plae under broiler for 1 - 2 minutes until the top turns golden brown. Be careful as it will go from golden brown to burnt very quickly. You can leave the oven door open a crack to watch it closely. A kitchen torch can also be used for browning.

Allow to cool before cutting and serving.