Heat oven to 177°C (163°C for dark or nonstick pan). Grease bottom and sides of 33x23-cm pan. In small bowl, dissolve coffee granules in boiling water.
In large bowl, beat cake mix, 1 cup water, the oil, eggs and coffee mixture with electric mixer on low speed 30 seconds, then on medium speed 2 minutes, scraping bowl occasionally. Pour into pan.
Bake as directed on box for 33x23-cm pan. Cool completely, about 1 hour.
In medium bowl, mix frosting and caramel topping. Frost cake with frosting mixture. Sprinkle with toffee candy. Store loosely covered.