Preheat oven to 350°F (175°C). Grease and flour two 9x5x3-inch loaf pans.
In a large bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the pumpkin puree.
In a separate bowl, combine the flour, baking soda, baking powder, salt, cinnamon, nutmeg, and cloves. Gradually stir the dry ingredients into the pumpkin mixture until just blended.
Fold in the walnuts, if desired. Divide the batter between the prepared pans.
Bake for 60 minutes in the preheated oven, or until a toothpick inserted into the center of the loaf comes out clean.
Let the loaves cool in the pans for 10 minutes before transferring to a wire rack to cool completely.
Interesting Facts
This type of pumpkin bread is popular in the state of Maine, especially during the fall season.
Pumpkin is a type of winter squash that is a good source of fiber, vitamin A, potassium, and other vitamins and minerals.
The addition of walnuts to this recipe adds a great crunch and flavor, but they can be omitted if desired.