Melt down coconut oil, half and half, stevia and vanilla extract in a double boiler and stir til combined. Then, add unsweetened baking chocolate until the desired consistency/sweetness. It's very important that you add the chocolate TO THE MIXTURE. If you add half and half or an alcohol extract to the melted chocolate, it will scald and you'll be adding coconut oil, butter or some other kind of fat in massive quantities until it smooths out again. Or you could burn the whole thing. The more half and half and stevia you add, the sweeter and more milk-like it'll be.
I like using coconut oil because it adds a wonderful velvety texture without imparting a coconut flavor, it stays solid at room temperature and will create a firmer chocolate than butter (but softer than cocoa butter so it's best stored in the fridge) and it's far easier to find and way cheaper than cocoa butter. I honestly think coconut oil yields a richer, smoother chocolate than actual cocoa butter as well.
Don't put your trust in anyone on this forum, including me. You are the key to your own success.