1. Preheat oven to 350 degrees. Butter a 10-by-15-inch jelly-roll pan. Line with parchment, leaving a 2-inch overhang on short sides; butter parchment.

2. In a bowl, whisk together butter, granulated sugar, and zest; whisk in eggs and salt. Add flour and cornmeal; whisk until just smooth. Spread batter evenly in pan. Bake until cake is dry to the touch and edges have begun to pull away from pan, about 15 minutes. Let cool completely.

3. Transfer cake to a work surface and cut into three layers, forming three 5-by-3-inch rectangles. Cover a rimmed baking sheet with a large sheet of plastic wrap; place one cake rectangle on it. Spread with pistachio gelato and freeze until firm, about 15 minutes. Top with second cake rectangle; spread with vanilla ice cream and return to freezer until firm, about 15 minutes. Top with third cake rectangle; spread with strawberry ice cream and freeze until firm, about 15 minutes. Wrap entire cake in plastic and freeze until ready to serve, up to 2 weeks.

4. Remove plastic and transfer cake to a serving dish. Beat heavy cream with confectioners' sugar on medium speed until stiff peaks form, about 1 minute. Frost cake with whipped cream. Freeze until firm, about 1 hour. (Once frozen, cake can be wrapped in plastic and frozen overnight.) Before serving, let cake stand at room temperature 10 minutes; then garnish top with strawberries and pistachios.