Whisk the coconut milk and yogurt together and heat up in a sauce pan or small pot over medium heat.
In a medium bowl, mix the egg, sugar, and salt together. Pour the heated milk mixture into the egg mixture.
Pour the combined mixtures back into the pan and heat over medium heat until it starts to simmer (about 10-15 minutes).
Remove from heat, then whisk in the stevia, cocoa, and vanilla. Let it set in the fridge.
While the filling is setting, make the tartlet shells using the recipe from the Patriotic Tartlets post.
Bake the tartlet shells for about 10 minutes, then place a couple of chocolate chips and pour the set filling into each tartlet shell. Bake for about 8 more minutes.
Add a marshmallow to each tartlet and broil for about 3-5 minutes (just enough to toast the marshmallow a little). Serve hot or cold!