1 cup (2 sticks) unsalted butter, cut into pieces, plus more for pan
1 1/4 cups all-purpose flour, plus more for pan
1 1/4 teaspoons coarse salt
1 cup unsweetened Dutch-process cocoa powder
2 teaspoons pure vanilla extract
4 large eggs, room temperature
1 1/2 cups granulated sugar
1/2 cup packed light-brown sugar
Royal Icing for Halloween Brownies
Preheat oven to 325 degrees. Butter a 9-by-13-inch baking pan, and line it with parchment, leaving a 2-inch overhang on 2 sides. Butter and flour parchment, tapping out excess.
Combine flour and salt in a small bowl. Melt butter in a medium saucepan over medium heat. Sift cocoa powder over butter, and whisk to combine. Let cool 3 minutes. Gently whisk in vanilla and eggs, then stir in sugars and flour mixture until just combined. Spread batter evenly in prepared pan.
Bake until top is firm and set, about 30 minutes. Transfer pan to a wire rack, and let cool for 20 minutes. Remove brownies from pan using parchment overhang, and let cool on wire rack. Cut brownies and decorate using royal icing, as desired. Brownies will keep at room temperature for up to 3 days.
This Halloween brownie recipe is adapted from the October 2008 issue of Martha Stewart Living.