Serves 8  to 12  Total Time ¼ hours, plus 30 minutes cooling

This recipe is excerpted from The Outdoor Cook by America’s Test Kitchen. Click here for more information and to purchase the book.

Why This Recipe Works: Grill-baking this supersize brownie in a cast-iron skillet and slicing it into wedges gives you the best of both worlds—a crispy edge and a fudgy middle—in every serving. To crank up the fudgy texture, this recipe includes an ingredient frequently found in fudge: marshmallows. Bittersweet chocolate chunks stirred into the batter at the end stud the brownie with gooey pockets of lush melted chocolate. Using indirect heat prevents the chocolate from burning and gets this brownie to its sweet spot in about an hour. (In the meantime, enjoy dinner.) In step 2, you can substitute bittersweet or semisweet chocolate chips for the chopped bittersweet chocolate, if desired, but the results will be less gooey. You will need a 12-inch cast-iron skillet. 

Ingredients

• 2 ounces marshmallows (about 8 large marshmallows)
• ½ cup plus 2 tablespoons warm tap water
• 4 tablespoons unsalted butter, cut into 4 pieces
• 2 ounces unsweetened -chocolate, chopped fine
• ⅓ cup (1 ounce) Dutch-processed cocoa powder
• 2½ cups (17½ ounces) sugar
• ½ cup vegetable oil
• 2 large eggs plus 2 large yolks
• 2 teaspoons vanilla extract
• 1¾ cups (8¾ ounces) all-purpose flour
• 1 teaspoon table salt
• 6 ounces bittersweet chocolate, chopped

Directions

1. Combine marshmallows, warm water, butter, unsweetened -chocolate, and cocoa in large bowl. Microwave at 50 percent power, -stirring occasionally, until chocolate is fully melted and mixture is smooth, 2 to 4 minutes. Let cool for 5 minutes.
2. Grease 12-inch cast-iron skillet. Whisk sugar, oil, eggs and yolks, and vanilla into marshmallow mixture until fully combined. Gently whisk in flour and salt until just incorporated. Stir in bittersweet chocolate. Transfer -batter to prepared skillet.
3. For a charcoal grill pen bottom vent completely. Light large -chimney starter filled with charcoal briquettes (6 quarts). When top coals are partially covered with ash, pour into steeply banked pile against 1 side of grill. Set cooking grate in place, cover, and open lid vent completely. Heat grill until hot, about 5 minutes. 
4. For a gas grill urn all burners to high; cover; and heat grill until hot, about 15 minutes. Leave primary burner on high and turn off other burner(s). (Adjust primary burner as needed to maintain grill temperature between 425 and 450 degrees; if using 3-burner grill, adjust primary burner and second burner.)
5. Place skillet on cooler side of grill and bake, covered, until toothpick inserted in center comes out with a few moist crumbs and batter attached (be careful not to overbake; brownie will continue to bake as it cools), 50 minutes to 1 hour 5 minutes, rotating skillet halfway through baking. Transfer skillet to wire rack and let cool for at least 30 minutes. Slice into wedges and serve.