Preheat oven to 350°. Line the bottom of a 13x9-inch baking dish with a thin dish towel. Brush the inside of 6 (7-ounce) ramekins with softened butter. Sprinkle each with 1 teaspoon granulated sugar. Place ramekins in baking dish.
In a small saucepan, combine › cup granulated sugar, brown sugar, ½ cup water, and espresso powder. Bring to a boil over medium heat. Remove from heat. Add chocolate, stirring until chocolate is melted. In a large bowl, whisk together cocoa powder, flour, and salt. Add hot chocolate mixture, whisking until smooth. Whisk in egg yolks.
In a medium bowl, beat egg whites and cream of tartar with a mixer at medium speed until foamy. Gradually add remaining 2 tablespoons sugar, beating at high speed just until stiff peaks form. Stir one-fourth of egg whites into chocolate mixture. Fold remaining egg whites into chocolate mixture. Gently ladle chocolate mixture into prepared ramekins. Add about 4 cups hot water to baking dish to a depth of about ½ inch.
Bake until puffed and set, about 20 minutes. Garnish with chopped chocolate and cocoa powder, if desired. Serve immediately.
Notes
A towel in the dish keeps the ramekins from moving in the dish.
Recipe by Louisiana Cookin' at https://louisianacookin.com/light-chocolate-souffles/