Preheat oven to 350. Melt chocolate and butter together then let cool slightly. Beat egg yolks and sugar until lemon colored. Add orange juice to sugar mixture. Add chocolate and egg whites then pour into buttered spring form pan. Sprinkle seabuckthorn berries evenly on top. Bake 55 minutes then cool 15 minutes. Run knife around edge to loosen. Let cool completely and remove from pan.