In a large bowl, combine the flour, sugar, baking powder, and salt. In a small bowl, using a hand whisk, beat the buttermilk, eggs, butter, and vanilla together, then gently mix into the flour just till combined. Do not overmix.
2 cups all-purpose flour, 1 tablespoon granulated sugar, 2 teaspoon baking powder, ½ teaspoon kosher salt, 1½ cups buttermilk, 2 large eggs, 4 tablespoons unsalted butter, 1 teaspoon pure vanilla extract