Heat the cream in a sauce pan until it just starts to simmer--bubbles should be just beginning to form at the edges of the pan.
Pour the cream over the chips. DO NOT STIR YET. If needed, you can shake the bowl to be sure the cream covers all the chips.
Cover the bowl with a plate and WAIT FIVE MINUTES. Time how long you wait. Too long or too short and the ganache will fail.
After five minutes, remove the plate and, starting in the middle, beging stirring the cream and chips mixture. At first it will be a kind of thin, milk chocolate, but it quickly begins to assume a darker color and a thicker texture. Continue mixing until there are no light swirls left.
WAIT ANOTHER FIFTEEN MINUTES before using. It takes a bit for it to thicken up. Fifteen minutes is just right for the desert in this blog. Waiting longer gives a thicker ganache, which would be fine for this dessert, too, but waiting thirty minutes or longer might make it harder to get a glossy shine to the finished product.
Notes
This recipe is from Natasha's Kitchen, where you can find more notes and uses for your ganache.