Heat oven to 400 degrees. In a medium bowl, whisk together flour, cornmeal, baking powder, baking soda, salt, and sugar. Using your fingers or a pastry cutter, cut butter into flour mixture. Using a wooden spoon, stir in 3/4 cup buttermilk until the mixture holds together.
Line a baking sheet with parchment paper. On a lightly floured work surface, roll out dough to a 1-inch thickness. Using a 2-inch-round cookie cutter or a drinking glass, cut out eight rounds, and place on prepared parchment; discard scraps of dough. Brush tops of biscuits with remaining tablespoon buttermilk. Bake until golden and puffy, about 12 minutes. If desired, spread with butter or honey. Serve warm.