Prep Time: 4 minutes
Total Time: 1 hour plus overnight chilling time
1 pound (16 ounces) good quality semi-sweet or bittersweet chocolate chips or bar chocolate, broken into pieces
2 sticks unsalted butter, (1/2 pound) cut into pieces
1/4 cup black coffee
8 large eggs
confectioners sugar (for serving)
1. Preheat Oven: Adjust oven rack to middle position. Preheat oven to 325 degrees.
2. Prep Pan: Place 2 large squares of heavy duty aluminum foil on working surface, one on top of the other. Place springform pan in center of foil and wrap foil snugly up around bottom of pan, pressing firmly against sides of pan. Spray inside of pan with nonstick cooking spray and line with a round of parchment paper cut to fit. Set pan inside a large metal roasting pan. Set pans aside.
3. Boil Water: Bring a large kettle or pot of water to a boil.
4. Melt Chocolate: Place chocolate, butter and coffee in a large, microwave safe bowl. Microwave until melted, stirring often to combine, about 1 – 2 minutes. Remove from microwave and set aside.
5. Beat Eggs: Using an electric stand mixer, whip eggs on highest speed until double in volume, about 5 – 8 minutes.
6. Combine Chocolate & Eggs: Pour about 1/3 of the whipped eggs into the chocolate and fold in gently, turning bowl and scraping down sides while you fold, until nearly all streaks are gone. Repeat with remaining egg in two batches. After final addition, fold in well several times so no streaks remain.
7. Transfer Batter: Pour batter into prepared pan. Lift springform pan up into the air about 2 inches, then drop. Do this once or twice to release air bubbles. Smooth top of cake.
8. Pour Water Bath: Place roasting pan with springform pan on the oven rack and pour boiling water around springform pan, being careful not to splash. Fill roasting pan until water reaches about half way up springform pan.
9. Bake Cake: Bake until a thin, shiny layer forms on top of cake, about 20 minutes for a 9 inch pan, about 25 for an 8 inch pan. Test that cake temperature is 140 degrees before removing from oven. Center of cake will appear loose, but will continue to cook once out of the oven.
10. Cool Cake: Gently remove springform pan from water bath and place on wire rack. Let cake cool completely, about 4 hours.
11. Finish Cake: Wrap cake with plastic wrap and refrigerate overnight.
12. Serve & Enjoy: Just before serving cake, run a knife around edge of springform pan, then release. To serve, dip a knife into hot water, wipe with a towel, then slice. Wipe knife clean, and repeat between cuts. Dust with confectioners sugar, if desired. Enjoy.