Preheat your oven to 350°F (175°C). Line a muffin tin with muffin liners or grease it lightly.
In a large mixing bowl, whisk together the sugar and vegetable oil until well combined.
Add the eggs one at a time, mixing after each addition. Then, stir in the pumpkin puree until smooth.
In another bowl, mix together the flour, baking soda, baking powder, spices (cinnamon, nutmeg, ginger), and salt.
Gradually add the dry ingredients to the pumpkin mixture, stirring until just combined. Be careful not to overmix.
If using, fold in the chopped nuts.
Spoon the batter into the prepared muffin tin, filling each cup about ⅔ full.
Bake for 20 minutes or until a toothpick inserted into the center of a muffin comes out clean.
Let the muffins cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.
For added sweetness, you can sprinkle a pinch of sugar on top of each muffin before baking.
Store the muffins in an airtight container at room temperature for 3-4 days or freeze for longer preservation.