Set up sous vide bath that will hold six quart jars
Set sous vide temperature to 115° F
Combine splenda and milk in a 6 quart pot
Heat while stirring to 180° F then remove from heat.
Chill in an ice water bath to 100° F then remove from ice water.
Add yogurt and vanilla to cooled milk and blend with immersion blender.
Ladle the milk / yogurt mixture into the quart jars and seal with lids
Place the jars in the sous vide bath and wait 24 hours