1For the cheesecake.
Preheat oven 325 degrees. Place a large roasting pan on the lower third rack of oven. Boil some water Spray a 9 inch springform pan and line the bottom with parchment paper.Wrap a double layer of foil around bottom and up sides of pan so water doesn't get in.
2Blend cream cheese until creamy. Add sugar and salt. Blend add eggs one at a time. Mix in sour cream, heavy cream and vanilla. Pour into pan and set pan in roaster. Carefully pour hot water around cake and about 1 inch up the sides. You don't have to do this but it keeps the cheesecake from cracking. Bake 45 minutes or until set. Let cool 1 hour and put in freezer overnight
3For the cake.
Preheat oven 350 degrees. Spray two 9 inch. round pans and line with parchment paper.
4Mix flour, cocoa powder, and salt and set aside. combine oil and sugar together and add eggs one at a time.Stir in baking soda and vinegar mixture. Add buttermilk and food coloring. Add dry ingredients. Mix well. Pour into pans and bake 30-35 minutes. Let cool completely.
5For the frosting.
Beat cream cheese and butter until smooth. Add marshmallow creme and mix well. Add powdered sugar.
Place 1 layer cake on plate. Remove cheesecake from freezer and place on cake trimming edges if needed. Top with other layer of cake and frost. Store in refrigerator