I suggested Chocolate Decadence and received rather enthusiastic approval. I've made this in the past but I seem to've lost that recipe and it's been a while. So I found this one and I modified it a little.
1 lb. bitter chocolate (I combined 275g Scharffenberger 99% w/ 200g Plantations Arriba 100% Ecuador Varietal)
5 oz. butter
3 T sugar
1 T flour
Melt butter and add chocolate. If you use a microwave, be very careful; overheated chocolate can only be thrown out.
Beat eggs with sugar until sugar is dissolved and eggs have tripled in volume. This will take about 8-10 minutes. Fold in the flour. Fold in the egg mixture into the chocolate ⅓ at a time. Be sure it's well mixed before adding more.
Prepare a 9 inch springform pan by cutting a round of wax paper to fit in the bottom of the pan. Leaving a small flange that is held by the spring of the pan can be useful. Grease the pan lightly and fit paper on bottom. Pour batter into pan and bake at 425°F. for 15 minutes. Center will be just beginning to set. Let cool completely in pan.
To serve remove from pan and remove wax paper. Place cake on serving dish. Serve it with whipped cream and/or a raspberry puree.
The original recipe called for dark chocolate and I don't think they had in mind how dark I like it. So, instead of 1 T of sugar, I changed that to 3 T. It is still incredibly dark then. If you are serving it to people that might not like really dark chocolate, you might want to increase that to 4 or even 6 T.
We'll see how this goes over tomorrow.