Preheat oven to 350ºF. Prepare a 10-12-cup Bundt pan by greasing well and dusting with flour.
In a bowl whisk together flour, cinnamon, nutmeg, baking soda, baking powder and salt.
In the bowl of a stand mixer, combine pumpkin, brown sugar, buttermilk, canola oil, eggs and vanilla. Mix until smooth.
Add dry ingredients in batches until combined. Stir in carrots, pineapple, coconut raisins and nuts (if using).
Pour batter into prepared pan and bake for 50-55 minutes or until a toothpick inserted into centre comes out clean.
Cool cake in pan for 15 minutes and then turn out onto rack. Drizzle with Sugar Glaze when completely cooled or ready to serve.