Springtime skillet lasagne

Ingredients

• 1 tablespoon olive oil
• 1 onion, finely chopped
• 500 gram pork and veal mince
• 540 gram jar tomato basil pasta sauce
• 2 180g jars mixed antipasto
• 1 bunch asparagus, trimmed, halved
• 4 fresh lasagne sheets
• White sauce
• 40 gram butter
• 1/4 cup plain flour
• 1 1/2 cup milk
• 1/2 cup grated parmesan cheese
• 1/2 cup grated tasty cheese
• mixed salad to serve