Preheat oven to 350 degrees F (175 degrees C).
Grease an 8x8 inch baking pan.
In a bowl, stir together the flour, baking powder, and salt.
In a separate bowl, stir together the melted butter, sugar, and vanilla. Using a spoon, mix in eggs one at a time. Gradually stir in your flour mixture, and divide the batter evenly amung two separate bowls.
Stir in cocoa powder and chocolate chips to one batter. In the second bowl of batter, stir in the pumpkin puree, walnuts, cinnamon, cloves, and nutmeg.
Spread 1/2 of the chocolate batter into the bottom of a greased 8x8 baking pan. Spread 1/2 of the pumpkin batter on top of that.
Add dollops of each of the remaining batters into the baking pan (this will make it easier to swirl). Then, drag a kitchen knife gently through the dollops of chocolate and pumpkin batter to create a swirled top.
Bake at 350 for 45-48 minutes. Enjoy!