I wanted to have slightly bitter caramel sauce - not as sweet as store-bought.
So I tried to make an easy microwave recipe for caramel sauce.

If you add the heavy cream all at once, this cools the sauce too rapidly and the caramel will harden.
Adjust the amount of heavy cream to suit the texture you want to achieve. If you want runny sauce, add more.
On the other hand, if you prefer thicker sauce, reduce the amount of cream!
The sauce will thicken as you chill it in the fridge.
I suggest you to use a clear microwave bowl so that you can see when the sauce becomes brown.
You can also decide how deep a brown you want the sauce to become. Recipe by Yukirinrin