Preheat the oven to 350 F /180C /gas mark 4. Lightly grease your spring-form cake pan bottom, line with baking paper, lock the ring in place and grease lightly.
Combine the flour, baking powder, soda, cinnamon, ginger, orange zest and the pinch of salt and stir using a whisk..
In another bowl whisk together the sugar, eggs and oil until smooth. Add the pumpkin puree and stir well to combine.
Add the flour mixture and pecans and stir just to combine (do not overstir).
Pour the batter into the prepared pan, smooth out the top with a spatula and bake for 1 hour in the centre of the oven.
Remove from the oven, leave to cool in the pan for 10 minutes, then run a spatula along the edges to ensure the cake doesn't stick to the ring and remove the ring.
To make the icing combine all the ingredients and decorate the cake (once completely cooled).
Use a whisk to combine the dry ingredients.
Do NOT overstir the batter.
Use readymade pumpkin puree or make your own. Cut a small sugar/culinary pumpkin in half (through the top) and place on a baking sheet lined with paper cut side down. Bake in a preheated oven at 190 C for about 40-50 minutes or until the top browns and comes away from the flesh. Remove from the oven, discard the seeds, then scoop out the pulp and place in a strainer. It will release water as it cools. Once cooled puree and make the cake. You can prepare the puree in advance and refrigerate until you are ready to use it.
Cool the cake completely before decorating with the frosting.
You can make the frosting ahead, refrigerate it and decorate the cake just before serving.
Freeze the cake without the frosting, covered, for up to 3 months.