Crush the Butterfinger bars in a sealed bag with a rolling pin, or pulse them briefly in a food processor, until you have coarse crumbs with a few small shards. Set 2 tablespoons aside for the tops.

Beat the peanut butter, softened butter, vanilla and salt together until uniform and slightly lighter in colour, about 1 minute.

Add the sifted powdered sugar in two additions, mixing until it disappears. Fold in the crushed bars by hand so the shards stay intact.

Scoop tablespoon portions and roll them into 1-inch balls. Set them on a parchment-lined tray and refrigerate for 30 minutes.

Combine the chocolate and coconut oil in a dry microwave-safe bowl. Heat at 50% power for 1 minute, stir, then continue in 20-second bursts, stirring after each, until only a few lumps remain. Stir those out off the heat.

Drop a chilled ball into the chocolate, lift it out on a fork and tap the fork against the rim so the excess drains back into the bowl.

Return each ball to the parchment and scatter a pinch of the reserved crumbs over the wet coating.

Leave at room temperature for about 20 minutes, until the shell is dry to the touch and snaps when bitten. Refrigerate for 10 minutes instead if the kitchen is warm.