Heat the heavy cream in a small saucepan until just about to simmer (do not boil).
Pour the hot cream over chopped chocolate in a bowl. Let sit for 1 minute, then stir until smooth.
Add vanilla extract and butter, and mix until glossy and fully combined.
Cover and refrigerate for 1–2 hours until firm enough to scoop.
Scoop small portions and roll into balls. Slightly shape if you want a bunny-style body.
Place on a lined tray and chill again for 20–30 minutes.
Melt coating chocolate using microwave or double boiler.
Dip each truffle into melted chocolate, coat evenly, and place on parchment paper.
While still soft, decorate with bunny tails, ears, and details using candy melts and toppings.
Let set completely before serving.