How to Make It
Beat butter and 1⁄2 cup of the powdered sugar with an electric mixer on medium speed until light and fluffy, about 4 minutes. Beat in 1⁄2 teaspoon of the vanilla. Whisk together flour, cornmeal, and salt in a bowl. Gradually add flour mixture to butter mixture, beating at low speed until combined, about 1 minute. Divide dough in half. Shape each half into a flat disk, and wrap in plastic wrap. Chill until firm, about 1 hour.
Preheat oven to 350°F. Roll 1 disk of dough 1⁄4 inch thick on a lightly floured work surface. Cut into 6 (4-inch) circles. Cut a 2 1⁄2-inch star from center of each circle (you should have 6 circles and 6 star cookies). Place cookies 1 inch apart on baking sheets lined with parchment paper. Bake in preheated oven until beginning to brown around edges, 12 to 14 minutes. Cool on baking sheets 5 minutes; transfer cookies to wire racks, and cool completely, about 20 minutes. Repeat process with remaining disk of dough, omitting star cutouts.
Gently stir together raspberries, blueberries, granulated sugar, and, if desired, liqueur. Let stand, stirring occasionally, until syrupy, about 20 minutes.
Meanwhile, place cream cheese, lemon juice, remaining 1⁄4 cup powdered sugar and 1⁄2 teaspoon vanilla in a medium bowl. Beat with an electric mixer on medium speed until creamy and smooth, about 1 minute.
Place cream in a separate medium bowl, and beat with an electric mixer on medium-high speed until foamy. Increase speed to high, and beat until soft peaks form. Stir one-fourth of whipped cream into cream cheese mixture. Gently fold remaining whipped cream into mixture. Cover and chill until ready to use.
To assemble each shortcake, place 1 circle cookie (without cutout) on a plate and top with about 1⁄4 cup whipped cream mixture. Top cream with 3 tablespoons berry mixture; top with 1 star-cutout cookie. Dust with powdered sugar before serving.