Place the finely chopped chocolate into a heat-proof mixing bowl. Ensure the pieces are uniform in size to promote even melting.
Pour the heavy cream into a small saucepan and place it over medium heat. Bring the cream to a gentle simmer, watching closely; you want small bubbles to form around the edges of the pan, but do not let it come to a rolling boil.
Remove the cream from the heat immediately and pour it directly over the chopped chocolate. Let the mixture sit undisturbed for 5 minutes.
Using the spatula, begin stirring the center of the bowl in small, tight circles. Gradually expand your motion until the cream and chocolate are fully emulsified into a glossy, smooth ganache.
Stir in the softened butter until completely incorporated to add a silky sheen to the mixture.
Cover the bowl with plastic wrap, pressing it directly onto the surface of the ganache to prevent a skin from forming. Refrigerate for at least 2 hours, or until the mixture is firm enough to scoop.
Use the cookie scoop to form small balls, placing them onto the parchment-lined baking sheet. If the mixture becomes too soft while rolling, return it to the refrigerator for 10 minutes.
Roll each ball in the cocoa powder until evenly coated. Shake off any excess powder before serving or storing.