Preheat the oven to 350 degrees F. Grease 7 standard muffin tins.
Mix the sugar, eggs, buttermilk and pumpkin until blended and set aside. Blend all the dry ingredients together in a separate bowl. Add the pumpkin mixture to the dry ingredients, mixing thoroughly. Stir in the melted butter.
Pour 3 ounces batter in each muffin cup of the prepared pan. Bake until a toothpick comes out clean, 15 to 20 minutes.