In a medium bowl whisk together the milk, eggs, sugar substitute, espresso powder or coffee, and vanilla extract until well blended. Pour into four 6-ounce custard cups or ramekins and place in a 10" large, flat bottom pan.
Fill the pan with water to 1/2" from the top of the custard cups. Bring the water to a boil over high heat. Reduce the heat to low, cover, and simmer for 10 minutes. Remove the cups from the skillet, cover with plastic wrap touching the surface of the custard, and refrigerate for 3 hours, or until chilled.
Garnish with the cinnamon and lemon twists. A teaspoon of sugar free raspberry or blackberry jam is also delightful!