Sounds very similar to MacIntoshe's Toffee bars which were sold in Canada, but I'm not sure if they were available in the USA. They were in a thin cardboard box about 2" x 3" with a plaid decorative motif...mostly a reddish plaid color. Yes, you could break them when they were cold, but I found it more fun to warm them up some...whereupon they got flexible and a bit stretchy. You would then clamp down on the bar with your teeth and worry off a chunk, like Fido chewing on a bone. You could then chew the stuff for ages. It was the World's longest lasting candy bar to eat...and that's what I really loved about them, aside from the flavour. You simply could not eat those things quickly.

They were very, very chewy. Good exercise for the jaws, but not so good for your teeth, I'm afraid. I gave a hunk of one to my dog once (a dachshund), and he nearly went crazy with it, cos it got stuck in his back teeth. He was chewing on it for a very long time.