Place chocolate chips in a small bowl. In a small saucepan, bring cream just to a boil. Pour over chocolate; whisk until smooth., For a pourable ganache, cool, stirring occasionally, until mixture reaches 85°-90° and is slightly thickened, about 40 minutes. Pour over cake, allowing some to drape down the sides. Spread ganache with a spatula if necessary to evenly coat, working quickly before it thickens. Let stand until set., For spreadable ganache, chill, stirring occasionally, until mixture reaches a spreading consistency. Spread over cake.