Slice cake crosswise twice,making 3 layers. Spread generous layer of coffee ice cream an inch or more thick on lower two layers. Replace top layer.
Whip cream; add sugar and taste. Whip in instant coffee. Frost entire cake with it. Crush toffee into small bits and sprinkle it generously over entire cake. Chill in refrigerator til ready to serve. Serves 6 to 8 (Seems to me the ice cream would melt in the fridge. Any ideas, anyone?)