Measure half and half into a medium-size microwave-safe bowl or measuring cup. Heat in the microwave on high power for 75-90 seconds or until it's boiling. Make sure to use a largeenough container to allow the liquid to boil without rising over the top.
Immediately pour over contents into a standard blender container and cover with the blender center cap removed. Holding several thicknesses of paper toweling over the center hole (to allow the steam to escape), blend on medium-high speed for 1 minute. Remove cover carefully and scrape down sides of blender container with a rubber spatula. Cover and blend again for another minute. The sauce should be smooth, silky and thick. Depending on the type of chocolate you use, the sauce may be too thick at this point. If you want to thin it a bit, add more half and half, 2-3 teaspoons at a time and blend briefly till combined. Continue until desired consistency is reached.
*Half and half can also be heated on the stovetop over medium heat until boiling. Stir frequently.
Don't attempt this recipe if you don't have a standard blender with a center cap that can be removed.