Preheat the oven to 350°F. Spray the bottom only of a 9x5-inch loaf pan with nonstick spray; set aside.
PREPARE THE BREAD BATTER:
In a large bowl, whisk together the pumpkin, sugars, milk, oil and egg whites in a large bowl.
In a separate bowl, whisk together the flour, baking powder, spice and salt. Add the flour mixture to the wet mixture and stir just until moistened.
PREPARE THE SWIRL:
In a medium bowl, use an electric mixer to combine the swirl ingredients until well blended.
ASSEMBLE THE BREAD:
Spoon half of the pumpkin batter into the prepared pan; spoon the swirl mixture evenly over the batter. Cover with the remaining pumpkin batter. Use a knife to gently drag through the batter and swirl it around, being careful not to touch the bottom or sides.
Bake for 1 hour, or until a toothpick inserted into the center comes out clean. Run a knife or a thin spatula around the edges of the pan to loosen the bread; cool the bread in the pan on a wire rack for 10 minutes. Remove the bread from the pan to the wire rack; let cool completely.