½ cup unsalted butter; melted 3/4 cup brown sugar 1 egg; room temperature 1 teaspoon vanilla extract 2¼ cup all purpose flour 1 teaspoon baking soda 2 teaspoons corn starch ¼ teaspoon salt ⅔ cup semi-sweet chocolate chips 6 tablespoons marshmallow fluff; frozen flaked Kosher salt
In a large bowl add melted butter, and brown sugar. Whisk. Add in egg and vanilla extract. Whisk. Add the all purpose flour, baking soda, salt, and corn starch. Fold. Pour in the semi-sweet chocolate chips. Fold.
Take a scoop of the dough (about 2 tablespoons) and flatten it into a round, thin, and flat disk. Do this 6 more times and place on the prepared cookie sheets.
Using a spoon, scoop 1 tablespoon of frozen marshmallow fluff and place it in the center of each of the cookie disks. Do not get the marshmallow fluff on the outer perimeter of the cookie disks.
Take another scoop of cookie dough (about 1 to 2 tablespoons) and flatten it into another disk. Place on top of your marshmallow fluff cookie disks and form them. Bake for 10 minutes at 350° F.
Allow the cookies to cool on the cookie sheet for 10 minutes. Transfer to a cooling rack and allow them to cool to room temperature. They taste best cold out of the refrigerator!