Step 1.  Combine cream, sweetener and lemon zest in a medium size saucepan. Measure the depth and calculate 2/3 of that amount. Mark your ruler at the 2/3 line.

Step 2.  Bring to a boil over medium heat. Continue to boil, stirring often to dissolve the sweetener. If the mixture begins to boil over, remove from heat and stir. Return to lowered heat. Cook until the mixture has reduced by 1/3 (your marked line). This should take between 8-12 minutes.

Step 3.  Remove the saucepan from heat and stir in the lemon juice.

Step 4.  Let the mixture cool until a skin forms, about 20 minutes. Strain through a fine-mesh strainer into a bowl and discard the skin and zest.

Step 5.  Divide the mixture into 4 ramekins or serving glasses.

Step 6.  Refrigerate uncovered, until set, at least 3 hours.

Step 7.  Serve with blueberries on top.