Chop the chocolate
If using a chocolate bar, chop it finely so it melts quickly and evenly. Place the chocolate in a heatproof bowl.
Heat the cream
Warm the heavy cream until it is hot and steaming, but not boiling aggressively. You can do this in the microwave in short bursts or in a small saucepan over medium-low heat.
Pour cream over chocolate
Pour the hot cream over the chopped chocolate. Let it sit for about 1 minute so the chocolate begins to soften.
Stir until smooth
Stir slowly from the center outward until the mixture becomes glossy and smooth. If a few pieces of chocolate remain, warm the bowl briefly and stir again.
Add salt or flavoring
Stir in sea salt or any flavor extract you are using. Add extracts sparingly so they do not overpower the chocolate.
Cool to the right consistency
For a drip cake, let the ganache cool until it is warm but no longer hot. It should flow from a spoon slowly and smoothly.
Use as desired
Drizzle over a chilled cake, pour over brownies, spread between cake layers, spoon over ice cream, or let it thicken for piping and filling.