Preparation

Wash sweet potatoes and stab the all over with a paring knife or fork. Place on a paper towel lined plate in a spoke fashion and microwave on high for 5 minutes. Turn the potatoes over and microwave for another 5 minutes. Let potatoes sit for 2 minutes. Check with a paring knife that the flesh is very tender. Remove them from the microwave and split open with a knife to let steam escape. Let cool for 10 minutes and scoop out the flesh. You should have 2 cups. Mash with a fork or potato masher. For extra smoothness, run the flesh through a food processor (optional). Alternatively you can roast the potatoes at 400 degrees until tender, about 1 hour. Don't peel and boil in water as this adds too much liquid to the flesh. This step can be done a day or so ahead, Cover and refrigerate.

Preheat oven to 350 degrees. Coat a half sheet pan (11.5 inches x 16.5 inches - measuring the inside) with cooking spray.

In a large bowl, whisk the granulated sugar, brown sugar, oil, sweet potato puree, eggs, and vanilla.

In another bowl, add the flour, baking powder, cinnamon, baking soda, salt, ginger, cloves, and nutmeg. Sift into the pumpkin mixture. Whisk until dry ingredients are just combined with the wet ingredients. Pour into the prepared sheet pan.

Bake for 20 minutes or until toothpick inserted into the center of the cake comes out clean. Transfer pan to a wire rack and let cool completely.

For the frosting, bang the still wrapped chocolate bar on the counter to break it into pieces. Put the pieces in a microwave safe bowl. Microwave 1 minute on high. Stir. If not completely melted, microwave for 10 seconds, stir. Repeat if necessary.

Beat cream cheese and butter in a stand mixer or with a hand mixer until smooth. Scrape in the melted chocolate and beat to combine. Add the powdered sugar and beat on lowest speed until sugar is incorporated. Increase the speed and beat until smooth.

Frost the cooled cake and top wi