How do I make clotted cream?

Does anyone have a good recipe for clotted cream? I cannot seem to find any in the states and all the online recipes I'm coming across are not authentic (they are whipping it an stuff)...I get raw (unpasteurized) cream from a farmer near me, but I cannot seem to find a recipe for an authentic clotted cream like Rodda's...help I'm dying for some authentic clotted cream...All I know is you take heavy cream, put in shallow pan and heat indirectly using a water bath or something, but I cannot find an exact recipe. I would really appreciate some help...