Steamed Chocolate Cake

Name: Steamed Chocolate Cake
Prep time: 5 min
Cook time: 1 h 30 min
Total time: 1 h 30 min
Yield: 10 portions
Ingredients: butter, unsalted; all purpose white flour; 6 eggs; 1 pinch salt; &frac45; tsp cream of tartar; 250 g dark chocolate; 100 g unsalted butter; 30 g olive oil; 150 g sugar; 50 g cornstarch; 1000 g water; 1 egg; 60 g sugar; 60 g butter, unsalted; 60 g dark chocolate