Prep the chocolate: Place the chopped sugar-free dark chocolate in a heatproof bowl.
The finer you chop it, the smoother the ganache will be.
Warm the cream: In a small saucepan, heat the heavy cream over medium-low until it’s steaming and small bubbles form around the edges. Do not boil.
Add the espresso: Whisk the instant espresso powder into the hot cream until fully dissolved. Stir in the pinch of salt.
Make the ganache: Pour the hot espresso cream over the chopped chocolate.
Let it sit undisturbed for 2 minutes, then stir slowly from the center outward until glossy and smooth. If a few pieces of chocolate remain, warm the bowl gently over a double boiler or in short 5–10 second microwave bursts, stirring each time.
Finish the flavor: Stir in the butter and vanilla until fully incorporated. Taste the ganache and, if you prefer it sweeter, whisk in 1–2 tablespoons of powdered erythritol or allulose until smooth.
Chill: Cover the bowl and refrigerate for 1–2 hours, until the ganache is firm but scoopable.
It should feel like firm peanut butter.
Prepare coatings: Place your chosen coatings in shallow dishes. Keep cocoa powder in one, nuts in another, and so on.
Scoop and roll: Using a teaspoon or small cookie scoop, portion the ganache into 1-inch mounds. Roll quickly between your palms to form smooth balls.
If it gets too soft, chill the mixture again for 10–15 minutes.
Coat: Roll each truffle in your chosen coating. For a bolder coffee note, mix a pinch of espresso powder into cocoa powder before rolling.
Set and serve: Arrange truffles on a parchment-lined tray and chill for 20–30 minutes to set. Serve slightly cool or at room temperature for the best texture.