Assemble a 9-inch springform pan. Line the bottom with the chocolate wafers, using about half the box. Fill in as many spaces as you can in a single layer, breaking the cookies as you need. Then keep going to use up half of the box. You will end up with almost a full double layer of cookies.
Add a layer of coffee ice cream about 1 inch thick. I used an ice cream spade to press it into place.
Drizzle a thick zig-zag layer of the caramel sauce over the ice cream using about ⅓ of the jar.
Next comes a layer of the ice cream bars. Place as many whole bars as you can in pan, then cut the remaining bars and place to fill in the spaces. Use your fingers to press gently, which will crack the outer chocolate coating of a few of them to help the bars spread and fill in the spaces.
Scatter about half of the bag of toffee bits over everything.
Now comes the only tricky part. Warm the hot fudge sauce just slightly in the microwave so that it is spreadable, but not hot. Using about ¾ of the jar, pour a layer over the toffee bits and use an offset spatula to create an even layer. If some of the toffee comes off and mixes into the fudge layer, don’t worry.
Add final layer of ice cream, filling up the space to the top of the pan. Cover tightly with plastic wrap and freeze overnight.
Unmold right before serving and top with a zigzag of the remaining microwaved hot fudge, a drizzle of the caramel sauce and a sprinkling of toffee and the nuts, if using. Cut into wedges, and serve immediately.