Preheat oven to 350 degrees F. Lightly grease the sides and bottom of an 9-inch loaf pan. Set aside.
In a medium mixing bowl whisk together the sugar, eggs, butter, 1 cup of milk, pumpkin and vanilla until combined.
In a large mixing bowl whisk together the flour, baking soda, baking powder, cinnamon, nutmeg, ginger, clove and salt. Use a rubber spatula to gently fold the dry ingredients into the egg mixture. Whisk until smooth.
Transfer about a cup of the batter to another small bowl and add the cocoa powder and espresso powder. Fold to combine. Add 1-2 tablespoons of milk to thin out a bit so that the consistency is the same as the all-pumpkin batter.
Pour half of the pumpkin batter into prepared loaf pan then pour chocolate batter over top. Pour the other half of the pumpkin batter into the loaf pan and tap pan on counter to remove any bubbles. Take a knife and swirl it through the batters, going from one end of the pan to the other. Top with turbinado sugar.
Bake at 350 degrees F for 1 hour to 1 hour and 15 minutes or until the center is set and firm to the touch and a skewer comes out with no wet batter. Allow the loaf to cool for 15 minutes in the pan then remove to a wire rack to cool completely.
See blog post above for important tips and suggestions.