Throughly coat a 10" (25cm) bundt pan with coconut oil including the center. Using a pastry brush or paper napkin, be sure to get all the nooks and crannies. Set aside. Preheat the oven to 350F (180C) and set an oven rack in the center.
In a medium mixing bowl, sift in the flour, corn starch, cocoa, baking soda, baking powder, cinnamon, nutmeg and salt. Set aside.
In a large mixing bowl, add the sugar, coconut oil, apple sauce, pumpkin puree and vanilla extract. Whisk until an emulsion is formed, until all the ingredients become incorporated and there's no separation. If the coconut oil solidifies, which it has for me before, gently warm the mixture in the microwave for 20 seconds at a time - the oil will melt again - give it a good whisk and you're off!.
Add the dry ingredients to the wet in two batches, folding the ingredients together just until there are no patches of flour. Try not to over mix - think gentle folding. Add the pecan bits and gently fold them in. Pour the mixture into the prepared bundt pan and give it a gentle tap on the counter to tap out any air bubbles. Bake at 350F (180C) for 50 to 55 minutes or until a toothpick comes out clean. The cake will be springy under gentle pressure.
Set cake, while still in the pan, on a cooling rack. Cool for 20 minutes, then turn out cake on to cooling rack. Allow cake to cool completely (several hours) before pouring the drizzle over the cake.
Before serving, give the drizzle a good stir. Do a test pour on the back of a spoon to see if the drizzle is the consistency you're after for the cake. It needs to be thick, but no so thick it doesn't drizzle. If it's too thick, let it come up to room temperature a bit. Pour over and around on cake. Serve any extra with individual slices or save it for ice cream :D .
The cake will store in a covered container, at room temperature for up to three days.