Preheat oven to 425 degrees and grease a 12 hole donut pan. In a large mixing bowl stir together flour, sugar, baking powder, nutmeg, and salt. Add buttermilk, eggs, and butter, stir until just combined.
Divide batter between prepared donut pan. Bake until toothpick comes out clean, 7 to 9 minutes. Let donuts cool in pans for 5 minutes then take them out of pan and let cool on a cooling rack.