This S’mores skillet cookie has extra toasty flavor thanks to a magic ingredient - browned butter. Browned butter is made by cooking unsalted butter until the milk solids turn brown. This yields a deep, rich, nutty flavor. Serve slices of this cookie warm with scoops of vanilla ice cream for the ultimate summer treat!
Melt the butter in a saucepan over medium heat. Use a light-colored metal saucepan so you can easily see the color of the butter change. Cook until the butter foams and steams. Swirl the pan occasionally as the foam subsides and watch closely as the butter turns golden brown and the milk solids drop to the bottom of the pan. Pour the browned butter and butter solids into a small bowl and let stand until cool but not solidified.
Use a pastry brush to coat a 10-inch cast iron pan with a little of the browned butter. Set aside.
In a large mixing bowl, combine the browned butter, sugars, eggs, and vanilla extract. Mix until well incorporated.
Add the flour, graham cracker crumbs, cornstarch and salt. Mix well until thick dough forms. Stir in the chocolate chips.
Press half of the cookie dough in the bottom of the prepared pan. Top with dollops of marshmallow cream. Place remaining cookie dough on top of the marshmallow cream using a spoon or an ice cream scoop. Allow some of the marshmallow cream to remain exposed. Smooth down the dough with a greased rubber spatula or by pressing it down with damp hands (dip hands in water, then press).
Bake for 25-30 minutes, or until the top of the cookie is well set and golden brown. (The center of the cookie will be gooey, and the edges crisp). Immediately garnish the top of the cookie with graham crackers and squares of the bar chocolate.
Let cool for 10 minutes before serving. Serve warm with vanilla ice cream.
While browning the butter you'll notice that it goes through several stages of bubbling. First it gets medium-sized soapy-looking bubbles with milk solids clinging to them. Then bubbles will get smaller as the butter cooks until it almost turns into a foam. Usually, just after the foaming part the butter will begin to brown. Watch the pan carefully while swirling it so you can best see what color the butter is turning. When it's deep golden, pour it into a bowl to cool.The center of this cookie stays gooey, so testing for doneness with a toothpick is out. The cookie is done when the edges are puffed and the top is golden. If you need extra insurance, stick an instant read thermometer in the center. A reading of 160F or higher is safe, as eggs are cooked at 160F. If the marshmallow cream doesn't get as brown as you'd like in the oven, stick it under the broiler for 2 minutes. Or use a chef's torch to toast it.
Keyword browned butter, dipped graham crackers, graham cracker crumbs, marshmallow cream, S'mores, semisweet chocolate chips