- Preheat oven to 350 degrees. Line a 5-cup ovenproof bowl with a double thickness of foil.
- Melt the chocolate with the water and sugar over low heat in a double boiler over medium- low heat, being careful not to burn the chocolate. Cool slightly. Transfer the chocolate mixture to a mixing bowl or to a food processor bowl fitted with the knife blade.
- Beat in the butter. Add the eggs one by one, followed by the vanilla extract, beating after each addition.
- Pour the mixture into the foil-lined mold. Bake 1 hour or until a thick crust has formed on top. It will still be soft under the crust.
- Remove from oven. (Note: The cake will collapse). Cool completely. Cover tightly and refrigerate until solid, 2 to 3 hours or overnight, or freeze. (Note: This can be done several days in advance).
- When ready to serve, whip the cream, sugar, and vanilla until stiff. Transfer to a piping bag with a star tip. Remove the snowball from the bowl and peel off the foil. Place on a serving dish, flat side down. Pipe rosettes of whipped cream over the entire surface until no chocolate shows. Chill until served. Garnish with chocolate leaves if desired. Leftovers freeze well, tightly wrapped– good enough for family anyway.