Beat egg whites in a metal mixing bowl until stiff but not dry. Add granulated sugar, and beat 1 minute more. Pour about one-third of the chocolate/tofu mixture onto the beaten whites, and mix gently. Mix in remaining chocolate/tofu mixture in two or three more batches. Pour cake batter into prepared spring-form pan.
Bake until slightly set around edges but still jiggly in center, for about 45 minutes. Remove from oven, and cool on a wire rack. When cool, cover and refrigerate for at least 2 hours and up to 2 days. The chocolate flavor is richer the next day.
To serve, run a knife around cake edge, and gently remove outside of pan. Slide cake from pan bottom onto a cake plate. Spread raspberry preserves over top of cake. Cover with fresh fruit. Use a hot knife to slice, wiping knife between cuts.