Preheat oven to 350F. Line a 15x10 inch baking pan with foil, extending foil over the edges.
In a large bowl stir together: flour, 1 ½ cup sugar, baking powder, cinnamon, baking soda, salt and ground cloves. Stir in pumpkin, 4 eggs and oil until well combined. Spread the batter in the prepared pan.
In a small pan melt ¾ of the chocolate chips over low heat. Stirring to ensure that all the chocolate is melted and not burning on the side of the pan. Remove from heat.
In a small bowl beat cream cheese and 1/3 cup sugar with a mixer at medium speed until well blended. Beat in 1 egg, milk, and melted chocolate. Spoon over pumpkin batter. Using the blade of a knife, swirl slightly to marble the pumpkin and chocolate mixture. Chop the remaining chocolate pieces and sprinkle over the chocolate pumpkin mixture.
Bake for 25 to 30 minutes or until puffed and toothpick comes out clean. Cool in pan over a wire rack. Using foil, lift uncut bars out of the pan. Cut into bars.