Bitter Leaf Breadcrumb Gratin

On a cold day, this is exactly what I crave: an ambrosial bubbling cheesy bean and herb gratin, spiked with a wake-up call of bitter wedges. The rich sauce makes this a very forgiving recipe – you can use any tightly packed heads of bitter leaves: chicory; round radicchio; or pointed Treviso radicchio. If using round radicchio, you’ll need one to two, each cut into eight wedges.