This is really easy to make, given how posh it looks coming out of the oven. Serves 2 or 3 people for lunch. It's a pastry-less quiche which makes it much simpler to do, and a bit healthier too probably.
Preheat the oven to 180ºC, and grease a metal baking tin of some sort whose edges go up at least one inch. (Or you could use a ceramic pot, probably wise to preheat that in the oven if so.)
Warm some marge/butter up in a pan and gently fry the red onion, with the rosemary sprinkled on top, stirring occasionally. It'll take about 10 minutes to soften nicely, so while that's doing, steam the asparagus: chop it into 3--5cm pieces (use the whole asparagus except for the hard bit right at the base) then put it in a sieve and suspend over boiling water for 5 minutes. Then run some cold water over the asparagus to stop them overcooking, and set to one side.
Whisk up the eggs, milk, salt & pepper, and parmesan cheese, whisking for about 3 or 4 minutes so there's plenty of air in the mixture. Then tip the onions into this mixture, and pour the mixture into your baking tin. Then put the asparagus in/on the top of the mixture, spreading them out in a nice even layer.
Bake at 180ºC for 25 to 30 minutes until it's looking nicely coloured on top. I served it with spinach & tomato salad, plus bread & butter.