Cook the pasta in a pan if water, following the packet instructions, then drain under cold water. Set aside.
Cut off the woody ends of the asparagus. Using a griddle pan, grill them until tender - or, if preferred, you can steam them over boiling water or add the to the pasta for the last 3 minutes of cooking, then drain.
Also, while the pasta is cooking, make the white sauce. Heat the milk with the onion and bay leaf. Don’t let it boil. Turn off the heat and rest whilst the pasta is cooking.
When the pasta is ready, remove the bay leaf and onion from the milk, then add your cheese and turn on the heat again. Stir until you get thick sauce. If you’re not using full fat cheese, first add the corn flour and heat the milk, stirring, until it has thickened. Then add the cheese.
Push three asparagus pieces through each pasta tube, then pour over the white sauce.
Serve immediately.