Place chopped chocolate in a medium-sized heatproof bowl and set aside.
In a small saucepan over medium heat, bring the cream to a boil. Once it begins to boil, remove cream from heat and whisk in the espresso powder.
Pour the cream over the chopped chocolate and allow the mixture to sit, untouched, for two minutes, then whisk smooth. Stir in the butter and vigorously whisk until smooth and shiny.
Cool to room temperature, then tightly cove the bowl with plastic wrap and refrigerate for 2 hours, or until firm enough to scoop.
Before you begin rolling your truffles, make sure you have enough room in your refrigerator for both baking sheets; the truffles must chill again before being dipped in the chocolate coating.
Line two large baking sheets with parchment paper and set them aside.
Scoop out about 3 teaspoons of the truffle filling and quickly roll it between your hands to form a ball. Transfer to the prepared baking sheet, and repeat with all truffles. Refrigerate the rolled truffles for at least 20 minutes before dipping in the chocolate.
In the meantime, you can temper your chocolate.
For the Chocolate Coating:
Fill a medium pot one-third full with water and bring it to a low simmer over medium heat. Place a heatproof bowl that will fit on top of the pan snugly, but will not touch the simmering water, on top of the pan. Reduce the heat to low and place two-thirds of the chocolate into the bowl. Place a candy thermometer into the chocolate and let it melt, stirring frequently with a silicon spatula. *Do not let the temperature of the chocolate exceed 120°F.
Once the chocolate has fully melted, remove the bowl from heat, but keep the pot of simmering water on the burner. Wipe the bottom of the bowl to remove any condensation.
Stir in the remaining chocolate, a little bit at a time, allowing what you've added to completely melt before adding more.
Set aside and allow the chocolate to cool to 82°F. Once the chocolate has reached 82°F, place it back over the simmering water and reheat to a temperature between 88°F and 91°F. Remove the bowl from heat once you have reached the correct temperature. The chocolate should be smooth and glossy, with no streaks.
Using a fork or candy dipper, dip each truffle in the chocolate, allowing excess chocolate to drip back into the bowl before transferring it back to the parchment paper line baked sheet. Top each truffle with two espresso beans.
Set aside and allow the chocolate to set before serving, about 1 hour.
Store in an airtight container, at room temperature, for up to 1 week.