From my wife:

Take a stick of butter and melt it in a pan on medium heat. Salted butter is best. Just butter, nothing else.

It takes about 10 minutes to turn a caramel color. Keep stirring with a heat safe spatula.

It will start crackling then get foamy then start to change color, and you'll see brown bits on the bottom. You have to experiment with how many brown bits you want.

Then she puts it in silicon molds and in the freezer to harden. Or you could put it in the fridge.

After it hardens she takes it out of the molds she puts it in Tupperware or a freezer bag so it doesn't take up so much room.

It tastes and has the consistency of toffee to me.

A tasty variation is to add bacon!