The cheesecake is from a bakery, but the sauce was thrown together by me.
Put some orange juice and mandarin oranges in a glass bowl, heat in the microwave, stiring every so often, about 25 minutes, or until the sauce has thickened. No need to crush the oranges, they'll fall apart. Dash in some orange bitters (I used Regan's), chill for a bit. Enjoy.