Place the 8 ounces of finely chopped bittersweet chocolate into a medium heat-proof bowl.
In a small saucepan over medium heat, bring the heavy cream to a gentle simmer, just until small bubbles appear around the edges.
Pour the hot cream over the chopped chocolate and let it sit undisturbed for 3 minutes to melt.
Whisk the mixture gently starting from the center until it forms a smooth, glossy ganache.
Stir in the peppermint extract and the softened butter until fully incorporated and shiny.
Cover the bowl with plastic wrap and refrigerate for at least 2 hours, or until the mixture is firm enough to scoop.
Using a small cookie scoop, form the ganache into uniform balls and place them on the parchment-lined baking sheet.
Refrigerate the formed balls for another 20 minutes to ensure they are cold before the final coating.
In a separate bowl, melt the semi-sweet chocolate chips and coconut oil together in the microwave in 30-second intervals, stirring between each, until smooth.
Using a fork, dip each chilled center into the melted chocolate, tap off the excess, and return to the parchment paper.
If using crushed peppermint, sprinkle the tops immediately before the coating sets.
Allow the chocolate to harden completely at room temperature or in the fridge for 15 minutes before serving.