Many people have asked me over the years, “What makes my toffee separate?”  I have blamed it on the butter, the pan, or the heat source.  After making two thousand pounds of toffee last year, I have come to the conclusion that the key to preventing separation lies in the dissolving of the sugar when you first start the batch.  My basic recipe is the standard 2 cups butter, 2 cups sugar, 1/4 cup water.  I always use AA grade sweet-cream butter.  If you use unsalted butter, make sure to add a bit of salt to the batch. 

I am also very careful about heating the mixture on low heat until the sugar is completely dissolved.  I will rub the warming mixture between my thumb and finger to see if there are any sugar crystals left.  When I am certain there are no more crystals, I turn up the heat and cook and stir the batch until it reaches about 300 degrees.  It will start to smoke at this point.  You need to use a heavy pan, preferably not aluminum, because aluminum will cause the sugar to change chemically and make the toffee more “sticky”.  I have made a lot of batches in aluminum and didn’t have a problem, but just know that there is a possibility.  And let’s face it—we all need to reduce any chance of failure!  

Good luck with your toffee!

Ruth