Preheat oven to 350°F. Spray baking dish with non-stick cooking spray. You can also opt to line with parchment paper for easy removal from dish. Set aside.
In a large bowl, whisk together flour, baking soda, salt, ginger, cinnamon, and allspice. Sift ingredients first, if possible. Set aside.
In a medium sized bowl, whisk together sweet potato purée, oil, vanilla, molasses, and sugar. Add these wet ingredients to your bowl of dry ingredients and combine well.
Pour batter into dish. Batter will be a bit sticky which is fine. Pat and spread batter with a spatula. Bake for 32 minutes at 350°F. Start making your frosting towards the end of your baking time. Let cake cool on a cooling rack for 20-30 minutes before adding frosting.
Vegan Cream Cheese Frosting:
In your stand mixer, combine cream cheese, vanilla extract, cornstarch, and confectioners sugar.
Spread over the top of your cooled, cake. Add festive sprinkles if desired!