Shortbread is the ultimate expression of four building blocks of baking: butter, sugar, flour, and salt. Here, it is flavored with orange zest. Try serving it with Sweet Corn Ice Cream.
Using an electric mixer fitted with the paddle attachment, beat butter and sugar until creamy and smooth, about 2 minutes. Add vanilla and zest. Beat well, scraping sides of bowl as necessary. With mixer on low speed, mix in flour, 2 tablespoons cornmeal, and salt until well combined, about 3 minutes. Form dough into two logs about 1 1/2 inches in diameter; wrap in plastic wrap, and chill at least 1 hour.
Preheat oven to 300 degrees. Place remaining 1/4 cup cornmeal on a sheet of parchment or waxed paper. Remove plastic from chilled dough; roll logs in cornmeal to coat. Slice into 1/4-inch rounds. Place on a baking sheet about 1 inch apart. Bake until pale golden all over, 25 to 30 minutes. Cool on a wire rack. Dust with sugar.