Preheat oven to 325°F. Lightly butter 2-quart shallow oval baking dish.
Into medium bowl, sift together cocoa powder and flour. In large bowl, with mixer on medium-high speed, beat eggs and sugar 5 to 10 minutes or until very thick and light yellow.
Reduce speed to low; add vanilla seeds, framboise (if using), and cocoa mixture. Mix just until combined. Slowly pour in butter; mix just until combined.
Pour mixture into prepared dish set in larger baking pan. Add hot tap water to pan to come halfway up side of dish.
Bake exactly 1 hour. A toothpick inserted 2 inches from side will come out clean. Center will appear very under-baked. Cool completely.
Serve with ice cream.