Preheat the oven to 350°F and grease an 8-inch square baking dish.
Sift the flour, baking powder and salt into a bowl.
Stir the melted butter, vanilla and sugar together in another bowl.
Mix the eggs into the butter mixture one at a time.
Stir the flour mixture into the egg mixture.
Divide this batter between 2 bowls.
Stir the chocolate chips and cocoa powder into one and the pumpkin, nuts and spices into the other.
Spread half of the chocolate batter in the bottom of the prepared pan.
Add half the pumpkin batter on top.
Now add dollops of both kinds of batter in the pan and pull a kitchen knife through the different dollops to get a swirly result.
Bake for 45 minutes or until cooked through.