Makes about 18
½ cup (packed) golden brown sugar
1 tablespoon unsweetened cocoa powder
3 large egg whites
¼ teaspoon kosher salt
½ cup sugar
2 teaspoons instant espresso powder
1 cup finely chopped toasted pecans
½ cup semisweet or bittersweet chocolate chips (optional)
18 pecan halves
Preheat oven to 300 degrees. Line a heavy large baking sheet with parchment paper.
In a small bowl, whisk brown sugar and cocoa to blend.
Using electric mixer, beat egg whites and salt until very soft peaks begin to form. With mixer running, gradually add sugar, then espresso powder; beat until medium peaks form. Beat in brown sugar mixture by tablespoonfuls. Continue beating until meringue is very stiff and glossy, 2 to 3 minutes. Fold in chopped pecans and chocolate chips. Drop mixture by rounded tablespoonfuls onto prepared sheet, spacing about 1 inch apart. Place 1 pecan half atop each meringue, pressing very lightly to adhere.
Bake meringues until dry but still slightly soft when pressed with finger, about 25 minutes. Turn off oven. Cool meringues in oven with door closed until crisp, about 1 ½ hours. Do Ahead: Meringues can be made up to 1 day ahead. Store airtight at room temperature.