Add sugar, salt and vanilla. Attach the silicone beater to the mixer, and add the sugar, salt and vanilla to the bowl. Pour the melted chocolate and butter into the bowl. Mix at 50% power (195 RPM) for 1 minute. Pause the mixer, this helps to not to overmix the ingredients, and allows time for you to prepare for the next step. Overmixing the ingredients would put too much air in and affect the end results.