Line bottom of 9-inch springform pan with parchment paper.
In small pot, heat water, salt, and Swerve over medium heat until salt and sweetener are dissolved.
Melt baking chocolate in double boiler or microwave.
Mix melted chocolate and butter in large bowl with electric mixer.
Beat in the hot water mixture.
Add in egg, one at a time, beating well after adding each.
Pour mix into prepared springform pan. Wrap outside well with foil.
Place springform pan in larger cake pan and add boiling water to the outside pan about 1 inch deep.
Bake cake in water bath for 45 minutes at 350°F. Remove and cool slightly on wire rack.
Chill cake overnight in refrigerator. Then remove side of springform pan.
Serving Size 12 Slices
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.