The perfect finish
Next, melt the butter in a large (about 25cm) nonstick, lidded frying pan over a medium heat. Pour in the egg mixture, lightly spread with a spatula to evenly cover the base of the pan, then season and cover with the lid. Cook for 4-5 mins until the bottom of the omelette is golden and set and the top is pale but lightly set. Covering the pan with a lid helps the top of the omelette to set, so you don’t end up with raw, foamy egg. No lid? Use an ovenproof pan and grill for 30 secs to set.
Slide a spatula around the omelette to loosen, then gently transfer to a plate. Cover half with the roasted cauliflower and spoon over the cheese sauce. Scatter with the parsley, remaining thyme leaves and a pinch of cayenne pepper. Fold the omelette over on itself and cut in half to serve.