Sep 14, 2023 · Preheat oven to 425°F, with a medium cast-iron skillet (10 inches, measured across top) inside on the center rack. In a bowl, whisk together flour, sugar, and salt. Purée eggs in a blender until pale and frothy, about 1 minute. Add flour mixture, milk, and vanilla. Purée until smooth, about 30 seconds (the batter will be thin).