Viral S’mores Skillet Cookie with Toasted Marshmallow Top Step-by-step instructions

Before you start

Before starting, heat the oven to 350°F (175°C) and position a rack in the center. Lightly butter an 8-inch cast iron skillet. Measure out all the ingredients: melt the butter and let it cool slightly, crush the graham crackers into coarse crumbs, and break the Hershey's bars into rectangles.

Have the egg and vanilla ready. The mini marshmallows should be at room temperature so they toast evenly. Set out a mixing bowl, whisk, rubber spatula, and measuring cups. This recipe comes together quickly, so having everything prepped makes the process smooth.

Instructions

Mix and Press

1. 1Make the Cookie Dough
   In a large mixing bowl, whisk together the melted butter, brown sugar, and granulated sugar until smooth and glossy. Add the egg and vanilla extract, and beat vigorously until fully combined and the mixture is lighter in color. Sprinkle the flour, baking soda, and salt over the wet ingredients, then stir with a rubber spatula until a thick, cohesive dough forms. Gently fold in the crushed graham cracker crumbs until evenly distributed. The dough will be soft but not sticky.
   Look for The dough is thick, holds together when pressed, and has graham cracker bits throughout.
   Tip Whisk the butter and sugars thoroughly—this helps dissolve the sugar and creates a smoother texture.
2. 2Press into Skillet
   Lightly butter an 8-inch cast iron skillet. Transfer the cookie dough into the skillet and press it into an even layer, using your fingers or the back of a spoon. Make sure the dough reaches the edges and is smooth on top. The dough will spread slightly as it bakes, so an even layer is key.
   Look for The dough is evenly pressed, touching the sides of the skillet, with a smooth surface.
   Tip If the dough is too sticky, lightly dampen your fingers with water to press it down.

The dough comes together quickly—it's thick, slightly sticky, and speckled with graham cracker crumbs. As you press it into the buttered skillet, it should hold its shape and feel smooth on top.

The kitchen smells like butter and brown sugar, a sweet promise of what's to come. Before moving on, make sure the dough is evenly distributed and reaches the edges, so it bakes uniformly.

Bake and Top

3. 3Bake the Cookie Base
   Place the skillet in the oven and bake at 350°F (175°C) for 15 minutes, until the edges are set and lightly golden, but the center is still soft and slightly underdone. The center should look puffy and barely set, as it will continue to cook from the residual heat of the skillet. Remove from the oven and let cool for 2 minutes before adding the toppings.
   Look for The edges are golden and firm, while the center is soft and slightly puffy.
   Tip Do not overbake—the cookie will finish cooking under the broiler with the toppings.
4. 4Add Chocolate and Marshmallows
   Arrange the Hershey's chocolate rectangles evenly over the warm cookie base, covering the surface. Sprinkle the mini marshmallows over the chocolate, making sure to cover the entire top. The heat from the cookie will begin to melt the chocolate and soften the marshmallows.
   Look for The chocolate starts to melt slightly, and the marshmallows are distributed evenly.
   Tip Press the chocolate gently into the cookie so it melts into the surface.
5. 5Broil Until Toasted
   Switch the oven to broil and place the skillet on the top rack, about 6 inches from the heat source. Broil for 2 minutes, watching closely, until the marshmallows are puffed and toasted to a golden-brown color with some charred spots. The chocolate should be melted and bubbly. Remove from the oven immediately.
   Look for Marshmallows are golden brown and puffy, with melted chocolate bubbling around them.
   Safe temperature 160°F (71°C) internal temperature (egg dishes)
   Tip Watch the broiler constantly—marshmallows can go from golden to burnt in seconds.

After 15 minutes, the edges of the cookie are golden and set, while the center is pale and puffy. The warm cookie gives off a buttery, toasty aroma. As you add the chocolate rectangles, they begin to soften and melt against the hot surface. The marshmallows sit like little white clouds, ready to transform under the broiler. The skillet is hot, so handle with care.

Broil and Serve

6. 6Let Rest and Serve
   Let the skillet cookie cool for 5 minutes so the chocolate and marshmallows set slightly, making it easier to scoop. Serve warm, with a scoop of vanilla ice cream on top if desired. Dig in with a spoon, pulling up gooey marshmallow strands and melted chocolate with each bite.
   Look for The top is toasted, the chocolate is molten, and the cookie is warm and soft.
   Tip For the full effect, serve directly from the skillet—it stays warm longer.

The broiler works fast: within 2 minutes, the marshmallows are puffed and toasted with golden-brown spots, and the chocolate is bubbling around them. The top is glossy and inviting, with a few charred edges that mimic a campfire. Letting it rest for 5 minutes allows the toppings to set just enough for clean scoops. The final dessert is a beautiful mess of gooey, warm, and crunchy layers.

Common mistakes

One common mistake is overbaking the cookie before adding the toppings, which makes it dry and crumbly. The center should be underdone when you pull it out, as it will continue to cook during the broil. Another mistake is not watching the broiler closely—marshmallows can burn in seconds.

Keep an eye on the skillet and rotate it if needed for even browning. Also, don't skip the graham cracker crumbs in the dough; they add essential texture and flavor. Finally, make sure the chocolate is broken into pieces that melt quickly; thick chunks might not melt through before the marshmallows are toasted.

How to tell it’s done

The cookie is done when the edges are set and lightly golden, and the center is soft and slightly puffy—it should not look raw or wet. The internal temperature of the cookie should reach 160°F (71°C) to ensure the egg is fully cooked. When you press the center gently, it should feel slightly firm but still give a little.

After broiling, the marshmallows should be golden brown with some charred spots, and the chocolate should be melted and bubbly. Let the skillet rest for 5 minutes before serving so the filling sets slightly and doesn't run everywhere.

• Egg dishes: 160°F (71°C) in the thickest part