Hi I'm a new user to the group, having just used the Hairy biker recipe for hollandaise sauce as a treat for Sunday brunch eggs Benedict.  This are the ingredients:    225g/8oz butter, cut into pieces 4 tbsp white wine vinegar 1 small shallot or ½ banana shallot, peeled and very finely chopped 10 black peppercorns 1 bay leaf 3 free-range egg yolks a pinch of sea salt flakes a pinch of caster sugar    And this is the preparation method:     For the hollandaise sauce, melt the butter slowly in a medium pan over   a low heat, stirring occasionally. Remove from the heat and pour the   butter into a jug. Add enough water into a medium saucepan to come a   third of the way up the sides. Bring to the boil, then reduce the heat   to a simmer. Put the vinegar, shallot, peppercorns and bay leaf in a   small saucepan over a high heat and bring to the boil. Cook for 1-2   minutes, or until reduced to two tablespoons of liquid. Remove from   the heat. Put the egg yolks in a heatproof bowl and place over the pan   of simmering water. Whisk the egg yolks with the salt and sugar until   pale. Pour the vinegar mixture through a fine sieve onto the yolks and   continue whisking until well combined. Slowly add the butter in a   steady stream whisking constantly until the sauce is smooth, thick and   shiny.   It split terribly and would not be rescued by adding it to a new egg yolk whisked in a clean bowl over a pan of simmering water. I had to use goats milk butter as I have a cows milk allergy. Would this make a difference? 225g of butter seems an awful lot? The taste was fine. 
Right, this post is old now. But for anyone that might come here looking for answers, here are a few tips. First of all, I should say I have made Hollandaise many many times as a chef, and sometimes it just doesn't want to come together no matter how precisely you follow the steps and use the right amounts. And there is nothing to do but start over. Now to the question asked.  Yes you can use goat's milk butter, absolutely nothing wrong with that. But as with cow's milk, a hollandaise is always easier to make if you clarify your butter first.  In terms of why it split, there could be a number of reasons. the most common ones have been mentioned here already. The heat might have been too high or the butter was poured in too fast. Or it simply didn't want to come together. A tip here, use a food processor if you have one to make your sauce it's much easier. Add egg yolk, vinegar, and salt to it and blend, once blended slowly stream in your butter. The food processor can "whisk" much faster than you, and you don't have to do two things at once. Just be careful with overheating if using the food processor, don't let it run with the ingredients in while doing something else. Pour the butter and get it done and then turn it off. Also, all emulsion sauces can be made this way. mayonnaise, aioli, bernaise, etc.  In saving a split sauce, there is only one thing to do, whisk one egg yolk with a tbs of water in a clean bowl and then slowly add in the split sauce. Sometimes it works, sometimes it doesn't. If it didn't work start over, that's really the only thing to do.   And last but not least, I haven't tried this recipe, but it does seem like an awful lot of butter. I always go with 165-175gr of butter for 3 egg yolks. It depends on the eggs. Large eggs = 175gr, medium eggs = 165gr. Hope this helps anyone that comes here to find answers. 