Marshmallow Crispy Cookies (Costco Copycat)

Preheat oven to 350 F. Line a baking sheet with parchment paper.
Start by browning the butter. You'll take ½ cup of butter and melt in a medium saucepan, and then continue to cook past the point of boiling. You will do this over medium heat, past the point of the butter foaming, until it turns a nice golden brown, and has a nutty smell. Make sure you are stirring and watching it, because it will turn from perfectly brown to burnt fairly quickly. Once finished browning, pour into a bowl and throw in the fridge or freezer for about 10 minutes to cool.
In a medium mixing bowl mix together brown butter and both sugars. Add the egg and vanilla and mix on low until smooth, about 30 seconds.
Slowly mix in the salt, baking soda and flour being careful not to over mix.
Fold in the rice krispies, followed by the mini marshmallows.
Scoop the dough into large balls, I like to use a 3 tablespoon cookie scoop for these. Place 4-5 cookies per cookie sheet as they spread thin and you'll need space.
Bake the cookies for 10-13 minutes. You're looking for a light golden brown around the edges. Be careful not to over bake, or you will lose the chewy center. Sprinkle with flaked salt.