Creme Anglaise Custard Sauce:
Adapted from: http://joepastry.com/category/pastry-components/creme-anglaise/
4 egg yolks
vanilla beans seeds (1 bean) or 1 ts. vanilla paste/extract
2 cups whole milk (for richer result use half milk and half cream)
1/3 cup erythritol (or xylitol or stevia to taste)
Pour the milk into a small saucepan and set over medium heat. Meanwhile, mix the vanilla and half the sweetener in and stir until it has dissolved. Have the yolks ready in a medium bowl, add the rest of the sugar and mix well. When the milk mixture starts to simmer, start tempering the yolks by pouring about half a cup of it into the yolks and whisking it in quickly. Add about another cup of the milk mixture, whisk, then pour all of it back into the saucepan. Return the pan to low heat and gently bring the mixture up to 183 degrees F, whisking steadily. Check before it reaches this temperature by dipping a wooden spoon in and swiping your finger across the custard film. If the custard has thickened enough that your finger leaves a path, don't wait for the temperature to reach 183, directly remove it from the heat and strain it into a bowl. Allow it to cool to room temperature (use an ice bath if you're in a rush). Store covered, with plastic wrap touching the surface so a skin won't form. Chill at least a few hours before using.
I recommend erythritol and stevia since they are the lowest in carbs, and this recipe does not require the stability that maltitol or other sugar alcohols would provide. (please DO NOT use splenda or aspartame, google their toxicity)