Preheat the oven:

Preheat your oven to 350°F (175°C). Line a muffin tin with paper liners or grease it lightly with cooking spray.

Mix dry ingredients:

In a large bowl, whisk together the flour, baking soda, baking powder, cinnamon, nutmeg, cloves, and salt until well combined.

Prepare wet ingredients:

In another bowl, whisk together the pumpkin puree, eggs, sugar, vegetable oil, and vanilla extract until smooth and well combined.

Combine wet and dry ingredients:

Gradually add the wet ingredients into the dry ingredients, stirring gently until just combined. Be careful not to overmix, as this can result in dense muffins.

Add optional mix-ins:

If you're adding walnuts or chocolate chips, fold them into the batter at this stage.

Fill the muffin tin:

Using a spoon or ice cream scoop, divide the batter evenly among the muffin cups, filling each about 2/3 of the way full.

Bake:

Bake for 18-22 minutes, or until a toothpick inserted into the center comes out clean or with just a few crumbs.

Cool and serve:

Let the muffins cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely. Serve warm or store in an airtight container.