You can use chocolate in candy molds. But not all chocolate is created equal. I have used chocolate chips and left over chocolate bars from other deserts and they melt very creamy. Using the wrong kind of chocolate may not get the desired results. For the chocolate to set firm, you may need to add a little paraffin while melting the chocolate, which is a food grade wax. Melt the chocolate using a double boiler as you do not want it to burn and add the paraffin in small pieces or even grated like cheese. There are lots of resources here if you search the forums and the internet you will find more specific instructions. You want it to firm up when you place the molds in the freezer for a few minutes to set.