Okay, I guessed on size of the pan. What did I do wrong? It wasn't firm; it wasn’t ‘solid’ to cut. Wonder if I need to be more firm in mixing it (I was afraid of making it tough) and forming it in the pan? My husband called it ‘shepherd’s pie déconstruit’. If doing again – just make half. It is big! Mild flavour for all those ingredients. Good with mash and peas.
I do hope someone can answer my question as to why it didn't hold together well. I made it as far as I can tell consistent with the directions.