In a bowl, combine flour, baking soda, cinnamon, baking powder, nutmeg and salt.
In the bowl of a mixer, add oil and sugar and cream (mix) until consistency of wet sand.
Add eggs and blend until smooth.
Reduce speed and add pumpkin and vanilla. Mix until combine, about 30 seconds.
Carefully add flour mixture and mix until combined being careful not to over-mix***
Pour batter into loaf pan reserving 1/2 cup.
Add melted chocolate to the reserved 1/2 cup batter and combine.
Pour chocolate batter on top of batter and swirl slightly with a knife. Don't stir and swirl too much or you won't have the marbled effect.
Bake 60 to 70 minutes at 350 degrees fahrenheit.
Test with a wooden pick. You want the pick to be clean or with a few cooked crumbs on it. It's not done if wet, moist batter is on it.
Cool 20 to 30 minutes in pan before inverting on wire rack to cool.
Serve warm or room temperature.
Store in an airtight container 3 days on counter or 1 week in refrigerator.
Notes
I use a 9x5.5-inch loaf pan.
I recommend using baking chocolate instead of chocolate chips. I use Ghirardelli baking bars. They're in a bar like a candy bar and melt smoother than chips.
*Any vegetable oil or coconut oil in the liquid state may be substituted.