Gently cook over medium heat (never boil!), stirring constantly, until chocolate has melted. Stir to make ingredients come together into a smooth sauce.
Continue gently cooking over medium to medium-low heat, stirring constantly, until sauce has reached your desired consistency.
Take off the heat, then serve hot for a thinner sauce, warm or at room temperature for a thicker sauce. Store leftover sauce refrigerated for up to 3 days, re-heat in a small saucepan with an additional splash of cream.
Heavy cream: Make sure to use heavy cream for the richest results. You can use half-and-half if that's all you have, but keep in mind that the sauce may come out a little thinner - you could reduce the liquid by ¼ cup to be on the safe side. Evaporated milk works in a pinch, too.
Chocolate: This really works with any chocolate you like. I used a semi-sweet baking chocolate. Be careful with white chocolate, it splits easily and must be melted over very moderate heat. If you want to use chocolate chips, please know that they contain less cocoa butter because they are usually meant to keep their shape - this means they take a little longer to melt and the end result is a little thicker.
Salt: Feel free to leave it out if you need to closely monitor sodium levels, it's not needed to make a great sauce.
If you need a smaller amount of chocolate sauce, it's absolutely fine to cut the ingredients in half, quarters or even into eights.
If you only have a microwave available, you can alter the recipe as follows: Heat ½ cup of cream in the microwave in a large, microwave-safe bowl in increments, until simmering. Stir in 1 cup of chocolate chips until melted and smooth. Thin with additional cream until it reaches your desired consistency.