1 tablespoon finely grated lemon zest plus 3/4 cup lemon juice (from 3 lemons)
8 large eggs, whites and yolks separated
1/4 teaspoon salt
2/3 cup cold heavy cream
1 1/2 cups raspberries (6 ounces)
Confectioners' sugar, for dusting
Wrap outside of a 3 1/2-cup souffle mold or four 6-ounce ramekins with parchment, extending 2 to 3 inches above rim (it should fit snugly). Secure with tape; set aside.
In a medium saucepan, whisk together granulated sugar, lemon zest and juice, egg yolks, and salt over medium-high. Cook, whisking constantly, until mixture is thick enough to coat the back of a spoon and small bubbles form around edge of pan, about 5 minutes (do not boil). Immediately remove from heat while continuing to whisk. Pour through a fine-mesh sieve into a heatproof bowl, pressing on lemon curd with a rubber spatula.
Place plastic wrap directly against surface of curd and refrigerate until cool, about 30 minutes (or up to overnight).
In a large bowl, using an electric mixer, beat egg whites on high until stiff peaks form, 2 minutes. Gently fold egg whites into cooled lemon curd. In the same large bowl, beat cream on high until stiff peaks form, 1 to 2 minutes. Gently fold whipped cream into lemon curd mixture. Pour into mold and freeze until firm, 6 hours (or up to overnight). To serve, remove parchment, top with raspberries and dust with confectioners' sugar.