Preheat oven to 425°F (220°C). Place a greased 9-inch cast-iron skillet in the oven to heat.
In a bowl, whisk together the jar contents.
In another bowl, beat eggs, then add buttermilk and melted butter. Stir into dry mix just until combined.
Carefully remove the hot skillet from oven, pour in the batter, and smooth the top.
Bake 20–25 minutes or until golden and a toothpick comes out clean.
Cool slightly, slice, and serve warm—best with honey butter!