Ingredients

• Vegetable oil spray
• ¾ cup all-purpose flour
• 3 tablespoons unsweetened Dutch-processed cocoa powder, plus more for sprinkling
• ¾ teaspoon baking powder
• ½ teaspoon table salt
• ¾ cup bittersweet chocolate chips
• 2 tablespoons unsalted butter, cut into 1-tablespoon pieces
• ¾ cup packed light brown sugar
• 1 large egg
• 2 tablespoons milk
• 12 regular-size marshmallows

Preparation:

• Set an oven rack in the top position and heat the oven to 350°F. Line a rimmed baking sheet with parchment paper and spray it with vegetable oil spray.
• In a medium bowl, whisk together the flour, cocoa powder, baking powder, and salt.
• In a large microwave-safe bowl, combine the chocolate chips and butter. Microwave at 50% power until melted, 3 to 5 minutes, stopping the microwave every minute to stir. Using oven mitts, carefully remove the bowl from the microwave and place it on the counter.
• Use the spatula to stir the melted chocolate and butter together until smooth. Add the brown sugar, egg, and milk to the melted chocolate mixture and whisk until smooth.
• Add the flour mixture to the chocolate mixture and use the rubber spatula to stir until no dry flour remains and a soft, fudgy dough forms.
• Use a 1-tablespoon measuring spoon to scoop twelve 2-tablespoon portions of dough onto the greased parchment-lined baking sheet. (Use a small spoon to help scoop out the dough—it will be sticky.) Let sit at room temperature for 10 minutes (this helps the cocoa hydrate and the dough firm up).
• Use your hands to roll the dough portions into balls. (If the dough is still too sticky, let it sit a few more minutes.) Arrange the balls 2 inches apart on the baking sheet. Gently flatten each dough ball a little with your fingers.
• Bake until the cookies are puffed and just beginning to crack but still very soft, about 7 minutes.
• Using oven mitts, remove the baking sheet from the oven. Quickly press 1 marshmallow, flat side down, into the center of each cookie. (The baking sheet will be hot—be careful!)
• Return the baking sheet to the oven and continue to bake until the cookie edges are set and the marshmallows are puffed and beginning to brown, 6 to 9 minutes.
• Remove the baking sheet from the oven and let the cookies cool on the sheet for at least 15 minutes to set. (The marshmallows will deflate a little as they cool—that’s OK.)
• Using a fine-mesh strainer, dust the tops with a little cocoa powder. Serve warm or at room temperature.

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