Preheat your oven to 350°F and line muffin tin with parchment rounds.
Prepare the chocolate cake batter as directed, and fill each mold halfway.
Bake for 10 minutes or until a toothpick comes out clean. Cool completely.
Scoop softened chocolate ice cream onto each cake base, smoothing it flat.
Freeze the cakes for 2 hours to set.
Heat heavy cream until steaming, then pour over chocolate chips to make ganache.
Spoon ganache over the frozen cakes, letting it drip elegantly.
Add crushed nuts or sprinkles, if desired, and freeze for another hour.