Preheat the oven to 350°F (175°C). Grease a 9×5-inch loaf pan or line it with parchment paper.
In a bowl, whisk together flour, baking soda, baking powder, salt, cinnamon, nutmeg, and cloves.
In another large bowl, whisk oil, brown sugar, granulated sugar, eggs, pumpkin puree, and vanilla until smooth.
Gently mix the dry mixture into the wet mixture till just combined. Do not overmix.
Add walnuts if you want.
Put batter into the prepared bread pan and smooth the border.
Bake for 55–60 minutes, till a toothpick in the center comes out clean.
Leave the bread cool in the pan for 10 minutes. Then move to a rack to cool completely before cutting into pieces.