Use plastic/saran wrap to line 6 cupcake wells in a cupcake pan; set aside.
Using the rim of a medium-sized glass or circular cookie-cutter, cut a circle into the brownie. Flatten, then press into the bottom and up the sides of the lined cupcake well. Repeat five more times to fill the rest of the cupcake wells.
Place a scoop of ice cream into the center of each brownie bowl, then use a spoon to make a divot into the center. Place about a tablespoon of Nutella into the divot, then use the spoon to slightly cover the Nutella. Freeze for at least 30 minutes.
Using a smaller glass, use the rim to cut six more circles from the brownie. Flatten, then press slightly on top of the ice cream bombes, making sure that all of the ice cream is covered. Wrap the plastic wrap tightly around each bombe, but leave them inside the cupcake pan. Freeze for at least 6 hours.
To make the magic shell, place the chocolate chips and the coconut oil in a microwave-safe bowl. Heat in the microwave until smooth and melted. Cool completely, then stir in the toffee bits.
To coat, stab a skewer into a brownie bombe, dip into the bowl of melted chocolate, and use a spoon to pour the chocolate over. Allow excess chocolate to drip off, then place onto a wax paper-lined baking sheet. Repeat with the rest of the brownie bombes. Eat immediately, or keep in the freezer for up to 6 months.