Wash the sweet potatoes and boil in their skins, covered, until it is fork tender, about 20 minutes. Preheat your oven to 375ºF. Peel your potatoes while still hot, mash them up with a fork and beat in your butter until it melts. Next beat in the eggs, one at a time, until well blended. Then toss in your brown sugar, vanilla and cream and blend well. If you decided to add the pecans and marshmallows now, do it now. Turn your mixture out into a well buttered 2 quart casserole. Decorate with the pineapple rings and cherries and bake in the oven for 20 to 25 minutes or until lightly brown.