- Preheat the oven to 350°F (180°C, 170° for fan ovens). 
- Grease a 14 cup Bundt pan well with butter. (If you only have a 12 cup Bundt pan, grease some cupcake pans or a small loaf pan or two.) Dust the pan(s) with flour, tapping out any excess.  
- Sift the flour, baking powder, baking soda, salt, ginger, cinnamon, nutmeg and cloves into a large bowl. Set aside. 
- Beat the butter and brown sugar together in the large bowl of an electric mixer fitted with a paddle attachment. This will take 2 or 3 minutes at medium speed. 
- Add the eggs, one at a time, beating well after each addition. 
- Don't forget to scrape down the bowl from time to time. 
- Reduce the mixer speed to low. 
- Add the flour alternately with the buttermilk (2 additions of each, starting with the flour), beating until just combined. 
- Beat in the pumpkin puree. 
- Pour the batter into the Bundt pan until it is just less than three-quarters full. (If you have leftover batter, consider making some cupcakes.) 
- Bake the cake for about 55 minutes. The outside should be beginning to turn a light golden brown colour, and a skewer inserted in the centre should come out clean. 
- Remove the Bundt pan from the oven and set it on a wire rack to cool. 
- After half an hour, carefully turn the cake out of the Bundt pan and on to the wire rack to cool completely. 
- For the glaze, mix the icing sugar gradually with the water or lemon juice, until a smooth, drizzle-able consistency is reached. (Go carefully, as you may need more or less liquid.) 
- Drizzle the glaze over the cooled cake. 
- Sprinkle with the chopped crystallised ginger, if using. 
- Allow the glaze to dry before slicing and serving.