Pre-heat the oven to 350 degrees.
Boil the sweet potatoes until fork tender. Let them cool and peel them and put them into a mixer.
Add the butter, vanilla, nutmeg, and cinnamon. Mix until the potatoes break down.
Next add the brown sugar, tangerine marmalade and grand Marnier. Mix until smooth.
Add eggs, and cream cheese, and heavy cream, mix until combined with sweet potato mixture.
Pulse the ginger snaps and the pecans in a food processor until they are broken down into crumbs. As you break down the gingersnaps pour in the melted butter.
Line a 9-inch spring form pan with parchment paper and pour the crust into the bottom. Flatten out the crust, making sure it is evenly spread and covers the entire bottom of the pan.
Bake at 350 degrees for 12 minutes.
Let the crust cool, then pour in the cheesecake mixture. Once the mixture has been poured into the pan, drop the pan on a table a few times to get rid of any air bubbles.
Place the pan back in the 350 degree oven and bake for 70 minutes.
Check the cheesecake, and if it still seems loose in the center put it back in the oven. The cake is done when you insert a skewer in the center and pull it out cleanly with no cake on it.
Allow the cheesecake to cool over night and firm up.
Slice and enjoy.