Prep the chocolate: Finely chop the sugar-free dark chocolate and place it in a heatproof bowl. The smaller the pieces, the smoother your ganache.
Warm the cream: In a small saucepan, heat heavy cream over medium-low heat until it just begins to steam and small bubbles form around the edges.
Do not boil.
Add espresso and sweetener: Whisk the instant espresso powder and powdered sweetener into the warm cream until dissolved. Taste and adjust sweetness as needed.
Combine with chocolate: Pour the hot cream mixture over the chopped chocolate. Let it sit undisturbed for 2 minutes to soften the chocolate.
Stir to make ganache: Add the butter, vanilla, and a pinch of salt.
Stir gently from the center outward until the mixture is glossy and fully smooth. If a few pieces remain, set the bowl over a barely simmering water bath and stir gently until melted.
Chill: Cover the bowl and refrigerate for 1.5–2 hours, or until the ganache is firm enough to scoop but not rock-hard.
Shape the truffles: Line a baking sheet with parchment. Using a small cookie scoop or teaspoon, portion the ganache into balls (about 1 tablespoon each).
Roll quickly between your palms to smooth. If it gets too soft, chill for 10 minutes and continue.
Coat: Place your chosen coatings in shallow bowls. Roll each truffle to coat evenly.
Tap off excess cocoa or crumbs.
Set and serve: Refrigerate the coated truffles for 20–30 minutes to set. Serve slightly chilled or at cool room temperature for the best texture.