1.   Preheat the oven to 180 C or 350 F

2.   Line a 20 cm or 8 inch spring form pan with parchment (bottom and sides). Take a long sheet of aluminum foil, fold in half and then wrap the exterior of the spring form pan to create a water seal for the pan. You will also need a shallow wide pan that the will have room for the spring form pan and a surrounding water bath (about 1/3 of the way up the side of the spring form pan)

3.   Place a small pot with about 2.5 cm or 1 inch of water over medium heat. Bring water to a simmer and reduce heat to low

4.   In a medium bowl (which will fit over the small pot of boiling water) add all the chocolate truffle ingredients. Place bowl over the pot with heated water. Stir as the ingredients melt and combine. It may take several minutes for the mixture to come to a smooth creamy state. Test chocolate to ensure the sugar has dissolved. Then remove from heat and set aside for a moment

5.   Into two separate mixing bowls, separate the egg yolks and whites

6.   When the chocolate has cooled slightly, add one egg yolk at a time and stir into the chocolate before adding the next. Repeat until all the yolks have been added

7.   To the egg whites bowl add the lemon juice (or sub with white vinegar) and whip at high speed to the firm peaks stage

8.   Add about 1 cup of whipped egg whites to the chocolate mixture. Stir briskly to combine. Then add about half of the chocolate mixture to the egg whites or half of the egg whites to the chocolate bowl and fold to combine. Scrape the bottom to ensure all the ingredients have been combined. Repeat with the rest of the ingredients. Do not break the egg white foam

9.   Pour batter into the spring form pan. Place the pan into the water bath and bake in the middle position of the oven for 20 -25 minutes. Test with toothpick and remove from oven when done

10.   Remove from water bath pot. Place on cooling rack and let cake cool completely in the pan before removing the sides and parchment

11.   Serve as is or with a light sprinkle of powdered cocoa. Enjoy!