Chop the dark chocolate fairly small and place in a large, heat-proof bowl. Set aside.
Combine cream, butter, and espresso powder in a small saucepan over medium heat. Stir occasionally to help blend the ingredients and dissolve the espresso powder, and bring to a gentle simmer.
Remove from heat and pour over the chopped chocolate. Allow to sit for 4-5 minutes, then whisk until chocolate is melted and mixture is smooth. Gently whisk in the Irish cream.
Pour ganache into a shallow baking dish, then refrigerate for at least 2 hours.
When ganache has firmed up, using a melon baller or small cookie scoop, create 1-inch balls and place on a parchment-lined baking sheet. Return pan to refrigerator for 45-60 minutes.
When ready to garnish, place sprinkles or cocoa powder in shallow dishes at your work space. Remove truffles from refrigerator, roll each one between the palms of your hands to tighten the ball shape, then roll in sprinkles or cocoa.
Place coated truffles back on parchment, on a serving plate, in an airtight container, or in your mouth.