Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners or grease it lightly.
In a large bowl, whisk together the pumpkin puree, vegetable oil, eggs, and vanilla until well combined.
In a separate bowl, mix the dry ingredients: flour, cocoa powder, sugar, baking soda, baking powder, and salt.
Gradually add the dry mixture to the wet ingredients, stirring until just combined. Avoid over-mixing.
If desired, fold in chocolate chips for extra richness and flavor.
Spoon the batter into the prepared muffin tin, filling each cup about two-thirds full.
Bake in the preheated oven for 18-22 minutes, or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the pan for 5-10 minutes before transferring them to a wire rack to cool completely.