Host: "It's caramel week. For your signature challenge today, Prue and Paul would love you to make 18 millionaire shortbreads. They have to be identical"

Prue Leith: "What we're looking for in a millionaire shortbread are three distinctive layers. A beautiful soft shortbread, a gooey yet firm caramel, and a gorgeous thin chocolate coating on the top."

Paul Hollywood: "The skill comes in getting the caramel just right. It has to be firm, but not chewy. They could put coffee in it or rum in it ... or orange in it. I'm looking for something a bit special, and I'd like something I've never had before."