Step 1

Adjust oven rack to middle position and heat oven to 475 degrees. Whisk flour, baking powder, baking soda, sugar, salt, Parmesan, and rosemary in large bowl. Combine buttermilk and 8 tablespoons melted butter in medium bowl, stirring until butter forms small clumps (see photo below).

Step 2

Add buttermilk mixture to dry ingredients and stir with rubber spatula until just incorporated and batter pulls away from sides of bowl. Using greased 1/4-cup dry measure, scoop level amount of batter and drop onto parchment-lined rimmed baking sheet (biscuits should measure about 2 1/4 inches in diameter and 1 1/4 inches high). Repeat with remaining batter, spacing biscuits about 1 1/2 inches apart. Bake until tops are golden brown and crisp, 12 to 14 minutes.

Step 3

Brush biscuit tops with remaining 2 tablespoons melted butter. Transfer to wire rack and let cool 5 minutes before serving.