This is a lovely cultural mishmash of a dish – perfect for an autumnal dinner with friends. You roast fennel, leeks and onion in the oven with classic Korean kimchi seasonings, then top them with a rich, savoury custard, cheddar and bread mixture – it crisps up beautifully in the oven. Korean red pepper flakes are readily available online, but you could substitute with smoked paprika and chipotle chilli flakes if needed. Serve with a crunchy green salad alongside.