I have made three tartes tatin recently and failed on the proper caramelizing of the sugar two of those times. The sugar and butter seem to

When I make Tarte Tatin, I cook the apples in the pan along with the sugar and butter, and the whole thing caramelizes along the way. Here is that step from my recipe: "Butter a 10-inch ovenproof deep fry pie pan heavily with the 2 tablespoons soft butter. Make sure you coat the bottom especially well. Sprinkle half of the 1/2 cup of sugar over the butter. Arrange 1/3 of the apples over the sugar. Sprinkle 1/3 of the melted butter over the apples. Repeat with 1/2 the remaining apples and butter, then a final layer of apples and butter. Put remaining sugar on top. Cook on top of the stove (over medium-low heat) for about 20 minutes, until apples have softened and begun to caramelize." Hope this helps.

I think you might be heating it too high but also possibly stirring it too hard so that the sugar does not have time to melt before it starts clumping up. Any caramel experts out there who have thoughts?

Thank you Rocky Rill and Pegeen. Sorry, I ran out of space when entering my question yesterday. When heating the butter and sugar they eventually separate and the sugar gets brown and very thick. If you let it cool it resembles toffee. I tried using a thick Mauviel frying pan recently when the cast iron pan wasn't working for me but that too didn't work. Am I heating the sugar and butter too quickly?

As Rocky Rill mentions above, not exactly sure what the problem looks like. In case it offers any helpful tips, here's an article by David Lebovitz on making caramel:

http://www.davidlebovitz.com/2008/01/how-to-make-the/

Your question doesn't give a lot to go on in diagnosing your problem. What happened to the sugar and butter? What do you mean by "failed?" The Alice Waters recipe I read has you caramelizing in a cast iron pan. If it's a black interior, that wouldn't be my choice. Too hard to see just how amber the caramel is getting against the dark background so can overcook before you know it. I've used an All-Clad French Skillet to make Tarte Tatin and it's easy to see the color change against the stainless steel background.