Preheat the oven to 350°F (175°C) and prepare a loaf pan.
In a mixing bowl, combine the dry ingredients: flour, baking soda, baking powder, salt, cinnamon, and nutmeg.
In another bowl, whisk together the wet ingredients: oil, pumpkin puree, sugar, and eggs until smooth.
Gradually add the dry mixture to the wet ingredients, stirring gently until just combined.
Fold in the nuts, if using, ensuring they are evenly distributed.
Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Bake in the preheated oven for 60-70 minutes, or until a toothpick inserted comes out clean.
Let the bread cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.