In a small saucepan over medium-low heat, mix together the chocolate chips, milk, coconut oil, vanilla extract and salt. Stir until melted and completely smooth. If you want to add powdered sugar, gradually stir it in now.

Let the pan cool for about 15 minutes (or until cool enough to place in the refrigerator) and then place the pan in the refrigerator for about 10-20 minutes, stirring after every 5 minutes, or until firm enough to spread on the cupcakes. I only need about 15 minutes but other people have needed more time (like an hour). If you forget about it and leave it in the refrigerator too long, it'll be too firm to spread, so be sure to keep checking on it. Very lightly reheat it on low heat, stirring constantly, until it's soft enough.

Spread 1 tablespoon of frosting on top of each cupcake for a thin layer and 1 1/2 - 2 tablespoons for a more generous portion. Can also be piped. If doing that, you'll likely need quite a bit more frosting than 1 tablespoon per cupcake. I wouldn't recommend piping a huge mound of frosting, though, as this frosting is very rich! If you have any leftover frosting, cover and store in the refrigerator. Gently reheat on low heat.

I keep the frosted cupcakes at room temperature for a day and then refrigerate, just to be safe.