I love having caramel with apples and I like it even better when it is homemade. I use Sweetened Condensed Milk, Dark Brown Sugar and Butter. I use about equal parts of all three, heat over medium heat until it is well blended and hot. It should settle into a thick caramel as it cools.
I did try to make it recently, but must have messed up my measurements somewhere as it didn't set as I needed it to. *sigh* I wanted to use it to make homemade caramel apples (never made those before), but alas it didn't work.
Hope it works for you... my favourite cake recipe is coming up soon (Kris, you will totally remember it once I make it and post the pics here).