This ganache thickens as it sits. The ganache used for the Inside-Out German Chocolate Cake should be pourable but thick enough to fully coat the cakes.
SourceMartha Stewart Living, January 2002
1 pound bittersweet or semisweet chocolate
2 1/2 cups heavy cream
Chop chocolate finely using a serrated knife; place in a large heat-proof bowl.
Bring cream to a boil over medium-high heat; pour directly over chopped chocolate. Allow to sit 10 minutes. Use a rubber spatula to gently stir chocolate and cream until well combined and smooth. Let sit at room temperature until cooled and just thickened, stirring occasionally, about 30 minutes, but up to an hour depending on the temperature of the room.