Preheat your oven to 350°F (175°C), and line a muffin tin with paper liners.
In a large mixing bowl, combine the pumpkin puree, vegetable oil, granulated sugar, and brown sugar. Mix until well blended.
Add the eggs to the sugar and pumpkin mixture, and beat well until fully integrated.
In another bowl, whisk together the all-purpose flour, cocoa powder, baking soda, baking powder, cinnamon, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing just until combined. Be careful not to overmix.
Fold in the chocolate chips if using, ensuring they’re evenly distributed throughout the batter.
Spoon the batter evenly into the prepared muffin tin, filling each cup about two-thirds full.
Bake in the preheated oven for 18 to 22 minutes, or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the tin for about 5 minutes before transferring them to a wire rack to cool completely.