Looking to rocky road ice cream for inspiration for these decadent treats, we topped our brownie base with a liberal amount of sweet marshmallow crème and then swirled it through the batter with a knife. While these brownies look gooey and messy with their shiny marshmallow swirl, we made the base nice and sturdy so it could support its delicious topping, and so the brownies could easily be packed for lunch or taken on a picnic. Unsweetened chocolate rather than bittersweet or semisweet kept the sweetness of these marshmallow-enhanced brownies in check. Swirling the marshmallow on top rather than hiding it as a layer within the brownie batter ensured this star ingredient wasn’t overwhelmed by the chocolate. Toasted walnuts (or pecans if you prefer) provided crunch and the requisite rockiness. The result is a textural masterpiece: dense, chocolaty brownie; crunchy, toasty chopped nuts; and rivers of smooth, gooey marshmallow.
Ingredients
- 8 tablespoons unsalted butter
- 3 ounces unsweetened chocolate, chopped coarse
- ⅔ cup (3⅓ ounces) all-purpose flour
- ½ teaspoon baking powder
- ¼ teaspoon salt
- 1 cup (7 ounces) sugar
- 2 large eggs
- 1 teaspoon vanilla extract
- ½ cup walnuts or pecans, toasted and chopped
- 1½ cups marshmallow crème
- Adjust oven rack to middle position and heat oven to 350 degrees. Make foil sling for 8-inch square baking pan by folding 2 long sheets of aluminum foil so each is 8 inches wide. Lay sheets of foil in pan perpendicular to each other, with extra foil hanging over edges of pan. Push foil into corners and up sides of pan, smoothing foil flush to pan. Grease foil.
- Microwave butter and chocolate in bowl at 50 percent power, stirring often, until melted, 1 to 3 minutes; let cool slightly.
- Whisk flour, baking powder, and salt together in second bowl. Whisk sugar, eggs, and vanilla together in large bowl. Whisk chocolate mixture into sugar mixture until combined. Using rubber spatula, stir in flour mixture until just incorporated.
- Transfer batter to prepared pan, smooth top, and sprinkle with walnuts. Using spoon, place small dollops of marshmallow crème over brownie batter. Using butter knife, swirl marshmallow through brownie batter. Bake until toothpick inserted in center comes out with few moist crumbs attached, 22 to 27 minutes, rotating pan halfway through baking.
- Let brownies cool completely in pan on wire rack, about 2 hours. Using foil overhang, remove brownies from pan. Cut into 16 squares before serving.
