Don’t be scared off by the spice in these truffles. It’s meant to be more of a tingle at the back of your throat after the truffle melts in your mouth. Think of it as a whisper, one you're not quite sure you even heard. The heat hits so faintly, you have to wonder if perhaps you only imagined it.
If you want a fierce, "hello, I'm here", kick of heat, then I offer two suggestions. 1. increase the amount to 1 teaspoon; or 2. add the chilies to the cream, and let it steep overnight in the fridge. This will intensify their flavor in the cream.