Similar to flan —but without the extra carbs— this creamy custard makes a refreshing finale to any spicy meal. This recipe can be made up to 1 day ahead, covered with plastic wrap and stored in the refrigerator.
In a medium-size heavy saucepan, combine heavy cream and cinnamon. Heat over medium heat, whisking constantly to thoroughly blend cinnamon into cream, just until cream begins to steam (do not boil). Remove from heat.
Heat oven to 300°F.
In a medium bowl, whisk eggs, egg yolks, sugar substitute and salt together until pale yellow and slightly thickened. Using a soup ladle and whisking constantly, very gradually pour in the hot cream. When all the cream has been added, whisk in the vanilla extract.
Pour about 1/2 cup cream mixture into each of six 4-ounce custard cups (or pour entire mixture into a 2-quart round baking dish). Place the cups or baking dish in a roasting pan. Carefully pour enough boiling water in the roasting pan to come halfway up the sides of the cups or baking dish.
Bake until custard is still slightly loose in center, about 30 minutes (for the baking dish, bake about 5 minutes more). Using an oven mitt, carefully remove cups from water bath.
To unmold, chill custard for at least 4 hours or overnight. Run a knife around edge of custard cups to loosen, invert onto a serving plate, and top with caramel syrup (optional).
Serve warm, at room temperature, or cold; top each serving with 1 tablespoon caramel syrup.