Individual Chilled Lemon Soufflés

Name: Individual Chilled Lemon Soufflés
Ingredients: 1/2 cup lemon juice from 2 or 3 lemons; 2 1/2 teaspoons grated lemon zest (grate before juicing); 1 (¼-ounce/7-gram) package gelatin , unflavored; 1 cup whole milk; 3/4 cup granulated sugar; 5 large egg whites at room temperature; 2 large egg yolks at room temperature; 1/4 teaspoon cornstarch; Pinch cream of tartar; 3/4 cup heavy cream; fresh mint leaves , raspberries, confectioners' sugar, or finely chopped pistachios for garnish (optional)