Line six cupcake wells with plastic wrap. Cut brownie circles using a medium glass or cookie cutter, flatten, and press them into the lined wells. This forms a sturdy bowl that will hold the ice cream perfectly.
Scoop ice cream into each brownie bowl, creating a small divot in the center. Fill the divot with about a tablespoon of Nutella, then cover lightly with ice cream. Freeze for at least 30 minutes to set.
Cut six more brownie circles using a smaller glass and gently press them on top of each ice cream bombe, covering the ice cream completely. Wrap tightly with plastic wrap, leaving them in the pan, and freeze for at least 6 hours.
In a microwave-safe bowl, melt chocolate chips with coconut oil until smooth. Allow it to cool slightly, then mix in Heath toffee bits for a crunchy coating.
Insert a skewer into each bombe and dip into the magic shell, letting excess chocolate drip off. Place on wax paper to harden. Repeat with all bombes. Serve immediately or store in the freezer.