Cream together butter and 2 cups sugar. Add the vanilla and mix until smooth. Beat 4 eggs and add to the creamed mixture and mix well, scraping sides of bowl if necessary.

In a separate bowl, sift together cocoa powder, flour, baking powder and salt.

Switching to a paddle attachment, gradually add to the wet ingredients, mixing well after each addition. Fold in the chocolate chips.

Liberally grease a 9 x 13 inch pan. Pour 3/4 of the batter into pan and smooth evenly.

In a small bowl, beat the cream cheese until smooth.

Add pumpkin, 3 Tablespoons sugar, remaining egg, cinnamon and nutmeg and mix on low until smooth.

Spoon pumpkin filling evenly over the pan of brownies. Then spoon remaining brownie batter over the pumpkin filling. Use a knife or spatulas to swirl and create a marbled design.

Bake at 350 degrees on the middle rack for about 25 minutes. Remove from oven and jiggle the pan; if the middle jiggles sloppily, put it back in the oven and bake for 2-4 minutes. Keep doing this until cracks just start to appear and the middle JUST stops jiggling. (I baked for 45 minutes, in 4 minute increments after 25 minutes.)

Remove from oven and cool on wire rack. When completely cool, cut into squares.