Preheat the oven to 350F. Line an 8x8 loaf pan and set aside.
In large bowl add sugar, eggs, melted butter, milk, vanilla extract and pumpkin puree (not pumpkin pie filling) Whisk until combined.
Add ¾ all purpose flour, baking powder, baking soda, salt and pumpkin pie spice. Mix until well combined.
Transfer ½ of the batter into a separate bowl, add ¼ cup of flour in one batter. Mix until well combined.
Add cocoa powder to the remaining batter. Mix until well combined.
Spoon some of the pumpkin batter into the lined loaf pan, and spread it out into a even layer on the bottom. Create alternating layers of the pumpkin and cocoa batters by topping the pumpkin batter with 3-4 generous spoonfuls of the cocoa batter, followed by 3-4 generous spoonfuls of the pumpkin batter, and so on. Continue until all the batter is used. (See the recipe video)
Bake for 50-55 minutes or until tooth pick inserted comes out clean. Let it cool in the pan for 10 minutes and then transfer it to a wire rack to cool completely. Slice and enjoy.