Preheat the oven to 350°F. Spray a half sheet pan (13 by 18 inches) with nonstick spray.
In a large bowl, mix flour, baking powder, baking soda, salt, cinnamon, and ground cloves. Set aside.
In the bowl of an electric mixer, cream 1 1/2 cup sugar and oil together on medium speed, and then add 4 eggs one at a time. Add pumpkin puree, and mix until smooth and creamy.
Add the flour and spice mixture to the pumpkin batter a little at a time, mixing on low speed and scraping down the sides as needed.
Pour the pumpkin batter into the baking pan in an even layer, and clean the mixing bowl. Set aside.
In a small microwavable bowl, heat 1/2 cup of the chocolate chips for 30 seconds. Stir and then microwave 10 seconds at a time until they are completely melted.
Add the melted chocolate and cream cheese to the mixing bowl, and mix on medium speed. Add 1 1/4 cup sugar, 1 egg and milk and mix until well incorporated.
Spoon dollops of the cream cheese mixture on top of the pumpkin batter and use a butter knife to swirl together.
Sprinkle remaining chocolate chips evenly over the top. Bake for 25-30 minutes.
Cool completely, then cover and refrigerate.