Reserve four spears of asparagus; thinly slice remaining asparagus. Bring a medium saucepan of water to the boil, add sliced asparagus and corn; boil 2 minutes or until heated through. Drain.

In a small bowl, whisk egg, flour and milk. Stir in asparagus, corn and onion; season.

Lightly spray a heated large non-stick frying pan with oil. Pour two cups of the batter into the pan, flatten slightly; cook 2 minutes or until bubbles appear. Turn fritters; cook until lightly browned on the other side. Transfer to serving plates. Repeat with remaining mixture.

Cut reserved asparagus spears diagonally in half. Lightly spray the same pan with oil, add ham and asparagus to heated pan; cook 2 minutes, turning halfway through cooking time, until lightly golden. Layer fritters with ricotta, ham and asparagus.