In a large bowl, beat the pumpkin puree together with the sugar, eggs and extra-virgin oil until smooth.
In another bowl combine the flour, pumpkin pie spice, cinnamon, salt and baking powder.
Slowly incorporate the dry ingredients into the wet ones, making sure of not over mixing. Add the chocolate chips and stir everything quickly together.
Divide the mixture into a non-stick muffin tin folded with paper cases, filling ¾ of each cup.
Bake for 20 minutes or until a skewer inserted in the center of a muffin comes out clean.
Remove the muffin pan from the oven. Cool the pumpkin muffins in the tin for 10 minutes, then take them out and serve.
Notes
How to make homemade pumpkin pie spice mix: 1 tablespoon pumpkin spice mix: 1½ teaspoons cinnamon, ½ teaspoon nutmeg, ½ teaspoon ginger, ¼ teaspoon allspice.