Preheat oven to 335F. Spray a 10-cup or larger bundt cake pan with a baking spray. I recommend using one with flour or starch to ensure the cake doesn't stick to the pan.

Combine all of the dry ingredients in a large mixing bowl: flour, sugars, baking powder, salt and spices. Whisk until well combined and uniform.

In a separate bowl, combine all the wet ingredients: melted butter, eggs, pumpkin and extracts. Whisk until smooth. Add in the melted white chocolate and stir until incorporated.

Combine the wet and dry ingredients and stir just until flour is incorporated; take care to not over mix. Transfer the cake batter into prepared pan and level off the top. Bake in preheated oven for approximately 1 hour 15 minutes, or until a toothpick inserted into the cake comes out clean. If you notice the top of your cake browning too quickly, turn oven temperature down to 325F and bake for longer.

Remove cake from oven and let cool for about 10 minutes in the pan. Then place a cake stand over the top and invert the cake onto the stand. Allow the cake to cool completely before pouring melted chocolate or chocolate sauce over the top.