Line 4 cups of a jumbo muffin pan with 4 pieces of plastic wrap, letting plastic wrap extend over edges.

Crumble doughnuts into pea-size pieces, and divide into 4 piles. Firmly press one-third of crumbs from each pile into bottom of each prepared muffin cup. Working quickly, spread 3 tablespoons coffee ice cream over crumbs. Drizzle 2 teaspoons caramel topping over ice cream, then sprinkle with 2 teaspoons toffee bits.

Place in freezer for at least 2 hours to firm up. Meanwhile, cover crumbs with plastic wrap to keep them from drying out.

Remove muffin pan from freezer and repeat layers, ending with doughnut crumbs. (You may have some ice cream left over.) Freeze for 3 hours, or overnight.

When ready to serve, microwave heavy cream in a medium bowl until boiling. Immediately whisk in chocolate chips. Let mixture cool for 10 minutes.

Lift cakes from muffin pan by using plastic wrap. Invert onto a cooling rack placed over a parchment-lined baking sheet. Frost cakes with chocolate mixture. (You may need to place cakes in freezer for a short time while you¿re icing them if ice cream begins to melt.)

Drizzle caramel sauce on 4 dessert plates. Place one fudge cake on each plate.