Position a rack in the center of the oven and preheat the oven to 325 F. In a large saucepan, combine the milk, sugar, coffee powder, butter and chocolate. Set over very low heat and stir on and off until the sugar dissolves and the solids melt; stir to blend. Do not boil. Remove from the heat and set aside to cool until no longer hot to the touch.
In a large mixing bowl, lightly whisk together the eggs, egg white, and vanilla; set aside. Place a sifter over a second bowl and measure into it the cocoa, flour , baking powder, and salt. Stir/drift the dry ingredients into the bowl and set aside. To prepare the crumb crust, coat the inside of a springform pan with cooking spray, add the crumbs, and rotate and tilt the pan until the entire inside is covered. Spread any excess crumbs over the pan bottom. Cut a piece of heavy-duty aluminum
foil (or two layers of regular foil) about 15 inches square, set the pan in the center of the foil, and pleat and crimp the foil tightly against the pan sides. This will prevent water from seeping into the pan during baking in the water bath.
Test the temperature of the chocolate liquid; if comfortable to touch, whisk a little chocolate into the egg mixture to warm it slightly, then whisk all the eggs into all the chocolate and blend very well. Whisk this mixture into the dry ingredients. When thoroughly blended (no flour mixture should be visible), pour the batter into the prepared pan.
Set the pan (in its foil jacket) in the center of a roasting pan and add hot water until it reaches about one third of the way up the pan sides. Set the pans in the oven and bake for 50 to 55 minutes, until the cake top is raised, shiny, and slightly springy when pressed with your finger. A cake tester inserted about 1 inch in from the edge will come out with a
few moist crumbs attached. Remove the pan from the water bath, cool on a wire rack for about 15 minutes, then peel away the foil jacket. Allow to cool for at least 45 minutes longer before serving, or refrigerate overnight.
Serving: Remove the side of the springform pan, leaving the cake on the pan bottom. The top requires no decoration, but you can sift on a light dusting of cocoa just before serving if you wish. Can be served warm, about 1 hour after baking, or can be baked up to 3 days in advance and refrigerated, covered. Bring to room temperature before serving if chilled. To use the remaining egg yolk.... Vanilla Custard Sauce
In a medium-sized saucepan, whisk together 1 cup of the milk, the egg and egg yolk, and the sugar. Dissolve the cornstarch in the remaining 1 tablespoon of milk, then whisk it in.
Set the saucepan over medium heat and cook, stirring off and on with a wooden spoon, for 4 to 5 minutes. Then whisk continuously for the next 2 minutes, until the custard is thick enough to coat a spoon. Turn the spoon over and draw a line down its back; if the line does not close up, the custard is done. To not allow the custard to come to a boil.
Remove from the heat, stir in the vanilla, then strain into a bowl. Let cool. Refrigerate until served. Writer's Comments: 1) I use a regular crumb crust because I could not get any of the crumbs
to stick to the springform pan by only using cooking spray.
2) Top with a raspberry sauce.
3) I usually serve 10.
4) Warm some water in another saucepan for the water bath before you
start. Special Equipment:
8x2 Springform Pan
Roasting pan large enough to hold springform pan for water bath