In a medium saucepan, combine the fat-free milk, monk fruit sugar, and vanilla extract. Whisk together over medium heat until the mixture is warmed but not boiling.
In a separate bowl, whisk the cornstarch and egg yolks together until smooth. This will help thicken the pudding.
Slowly add about 1/2 cup of the warm milk mixture to the cornstarch and egg yolks, whisking continuously. This step is essential to prevent the eggs from scrambling.
Pour the tempered egg mixture back into the saucepan with the remaining milk mixture. Continue to whisk over medium heat until it thickens, about 5-7 minutes. Remove from heat.
Chop the semi-sweet baking chocolate and add it to the thickened pudding. Stir until fully melted and incorporated, creating a rich chocolate pudding.
Transfer the pudding to a bowl, cover it with plastic wrap (pressing it directly onto the surface to prevent a skin from forming), and let it cool for at least 30 minutes.
Once the pudding is cool, begin layering it in your serving glasses. Start with a layer of chocolate pudding, followed by a layer of whipped topping. Repeat the layers until the glasses are filled, finishing with a dollop of whipped topping on top.
Refrigerate the assembled Chocolate Parfaits for at least 1 hour before serving to allow the flavors to meld. Enjoy chilled!