This recipe is used to make the nougatine crown, a mixture of chopped nuts and caramel, that is the traditional base for a Croquembouche. The nougatine crown remains malleable for a while as it cools, allowing it to be manipulated into shapes. Here, it is formed in a tart shell. When cool, it is unmolded and turned upside down to form the base. Triangles of nougatine are cut from another piece, made thinner with a rolling pin, and attached to the base with still-warm caramel.