I did not follow the recipe exactly and it still turned out well.
#1 I used salted butter because that's what I had and it's possibly a TAD too salty. Next time I will use unsalted.
#2 I successfully doubled the amount of caramel. It wasn't caramel-ly enough and the extra liquid didn't break it or mess up the consistency. I also had a little trouble with the caramel itself- it did take longer to brown and I was worried that it would become candy before caramel so I (CAREFULLY) added a tbsp of water to the boil and Voila! It got brown.
#3 I felt this needed more than 45 minutes to meld. The powdered sugar was still gritty and it was too buttery. I refrigerated the icing overnight, broke it up over a warm water bath, then whipped it. Increasing the caramel stretched it enough to exactly cover 18 small cupcakes with nothing left over. If you're icing a cake you'll need to double this recipe.
The spreading consistency was similar to peanut butter, good for piping. I would use it again. Good flavor and easy.
I followed the recipe exactly.