Heat the cream over low heat until just simmering. Do not boil.
Remove cream from heat and pour over chocolate chips.
Place a piece of aluminum foil over the bowl and seal.
Let the cream/chocolate chips sit for 5 minutes without stirring.
Remove the foil.
Stir until the chocolate chips have melted and mixture is smooth and well-combined.
Let the ganache sit, uncovered, for 30 minutes, stirring occasionally, to set up before using.
Notes
Chocolate: Using a quality chocolate chip makes a difference. Some cheap chocolate chips are made with extra fillers and binders that keep them from melting properly.
Heavy cream: Please do NOT substitute half-and-half. It will give you a thinner, runny ganache.