Ingredients
Method
In a glass measuring cup, whisk together 1¼ cups unsweetened cold-brew concentrate, ¼ cup sugar, and 2 tsp. cognac until sugar has dissolved.
Pour coffee mixture into a metal loaf pan, cover with aluminum foil, and place in the freezer. After 1 hour, remove loaf pan, use a fork to scrape up any ice crystals that have begun to form around edges of pan, and return to freezer for another hour. Continue to freeze, scraping and breaking up larger ice crystals once an hour, for a total of 3–6 hours (the timing will vary depending on the exact temperature of your freezer). The granita is ready to serve when it’s reached the texture of snow rather than slush.
Meanwhile, in a small mixing bowl, whisk together ½ cup heavy cream, ¼ cup mascarpone, 1 tsp. vanilla extract, if using, and remaining 1 Tbsp. sugar until sugar has dissolved and mixture reaches the texture of whipped cream, about 2 minutes.
To serve, divide granita into 4 small glasses or dessert bowls, top with mascarpone mixture, and sift over 1 tsp. unsweetened cocoa powder.