In a small saucepan, combine heavy whipping cream, butter, and flavor extract (if using). Heat to a boil, remove from heat.

Pour hot cream mixture into bowl of chocolate chips. Let sit for 3-5 minutes.

Starting in the middle of the bowl, slowly start stirring the chocolate and cream until all of the chocolate is melted and the cream has disappeared into it – it should be smooth.

Cover with plastic wrap, preferably resting right on top of the surface – this prevents a skin from forming while it cools.

Allow to cool to room temperature, chill until cold, then whip with a stand or electric hand mixer for a minute or so, until fluffy.