Preheat oven to 350°F (175°C) and line a muffin tin with paper liners.

In a large bowl whisk pumpkin puree, sugar, brown sugar, oil, eggs, vanilla extract, and milk until smooth.

In another bowl mix flour, pumpkin spice, cinnamon, baking soda, baking powder, and salt.

Gradually combine dry ingredients into the wet mixture and stir gently until just combined.

Fold in chocolate chips or nuts if using.

Fill muffin liners about ¾ full with batter.

Bake for 18–22 minutes or until a toothpick inserted in the center comes out clean.

Let muffins cool for 10 minutes before serving.