Bring a large pot of lightly salted water to the boil. Cook lasagne sheets in boiling water for 8 to 10 minutes or until al dente. Drain and cut in half crosswise.
Melt margarine in a frying pan over medium heat. Saute garlic just until fragrant. Stir in the flour until no lumps remain. Gradually mix in milk and season with thyme. Simmer sauce gently until thick. Remove from heat.
Grease a 23cm square baking dish. Layer lasagne, sauce, asparagus, ham and mozzarella cheese in three layers, each starting with lasagne and ending with cheese on the top.
Cover the dish and cook in the microwave on HIGH for 9 to 10 minutes or until cheese is melted and bubbly. Time may vary depending on the oven used. Let stand for 5 to 10 minutes before serving.