Preheat the oven to 200°C. Coat a 20-cm square baking dish (2-l capacity) with cooking spray. Cook macaroni according to the packet directions. Drain and pour back into the saucepan, cover and set aside.
Whisk ¼ cup milk with flour in a small bowl until smooth. Set aside. Heat rest of milk in a medium, heavy-based saucepan over medium heat until steaming. Add flour mixture and cook, whisking constantly, until sauce boils and thickens, 2 to 3 minutes. Remove from heat. Add Swiss cheese and ⅓ cup cheddar cheese, stirring until melted. Stir in cottage cheese, mustard, nutmeg, parsley and pepper.
Cook spinach according to the packet directions. Drain, refresh under cold water and press out excess moisture. Stir in corn and peas.
Add cheese sauce to the macaroni. Spread half of the macaroni mixture in the baking dish. Spoon spinach mixture on top. Spread remaining macaroni mixture over the spinach layer. Combine wheatgerm with remaining cheese and rub in margarine. Sprinkle over macaroni.
Bake until bubbly and golden, 25 to 30 minutes. Serve with a mixed leaf salad.