Preheat oven to 350°F. and lightly grease muffin cups.
In a large bowl, combine the sugar, butter and molasses; beat well with an electric mixer. Add the egg and pumpkin, beating until smooth.
In a separate bowl, whisk together the flour, baking soda and salt. Add to pumpkin mixture, stirring just until moistened (the batter will be thick and lumpy).
Fill the muffin cups half full and bake for about 20 minutes, or until toothpick inserted in center comes out clean.