Make the Cupcakes:

1. Preheat the oven to 350 degrees and line a cupcake pan with cupcake liners.
2. Add butter, oil and milk to a large mixer bowl and whisk until smooth.
3. Add the brown sugar and whisk until smooth.
4. Add the vanilla extract and eggs and whisk until smooth.
5. In a separate medium-sized bowl, combine the flour, baking powder, baking soda, cinnamon, nutmeg, ginger, cloves and salt.
6. Add the dry ingredients to the wet ingredients and mix until smooth.
7. Fold in the pumpkin puree and chocolate chips until well combined.
8. Fill each cupcake liner about ¾ full.
9. Bake cupcakes for 21-23 minutes, or until a toothpick inserted in the middle comes out with a few crumbs.
10. Remove cupcakes from the oven and allow to cool for 2-3 minutes, then remove to a cooling rack to finish cooling.

Make the Frosting:

1. Combine the cream cheese and butter and mix until smooth.
2. Add about half of the powdered sugar and mix until smooth.
3. Add the vanilla extract and mix until smooth.
4. Add the remaining powdered sugar and mix until smooth.
5. Use a large round piping tip to pipe swirls onto the cupcakes. Top with a drizzle of chocolate sauce, if desired.