Preheat the oven to 350°F and grease an 8-inch square baking dish.
Stir the flour with the salt and baking powder.
Mix the melted butter, vanilla and sugar in another bowl.
Mix the eggs into the butter mixture one at a time.
Gradually mix in the flour mixture and then divide the batter between 2 bowls.
Mix the pumpkin, walnuts and spices into one mixture and the chocolate and cocoa powder into the other.
Spread half of the chocolate mixture into the prepared pan followed by half of the pumpkin mixture.
Add the remaining batters on top in dollops then drag a butter knife through them to swirl.
Bake for 45 minutes or until done, then cool, slice, and serve.