1

Heat half the oil in a large non-stick frying pan over high heat. Cook beef, turning, in batches, for 2–3 minutes or until browned. Transfer to a plate.

2

Heat remaining oil in same pan over high heat. Cook eggplant, in batches, for 2 minutes each side or until golden. Transfer to a plate. Cook zucchini, in batches, for 1–2 minutes each side or until golden. Transfer to a plate.

3

Cook onion in same pan over medium heat, stirring, for 5 minutes or until softened. Add garlic and cook for 1 minute or until fragrant. Add tomatoes and tomato paste and bring to the boil. Remove from heat. Season with salt and pepper. Stir in chopped oregano.

4

Place half the beef in the base of a 4.5 litre (18-cup) slow cooker. Pour over half the tomato mixture. Top with half the eggplant and half the zucchini. Continue layering with remaining beef, eggplant and zucchini. Pour over remaining tomato mixture. Cook, covered, on low for 8 hours (or high for 4 hours). Carefully transfer beef mixture into a 2.5 litre (10-cup) capacity ovenproof dish.

5

Preheat grill on high. Bring liquid stock to the boil in a medium saucepan over high heat. Reduce heat to medium-low and stir in polenta in a thin, steady stream. Cook, stirring constantly, for 5–7 minutes or until polenta boils and thickens. Remove from heat. Stir in half the parmesan. Season with salt and pepper. Pour hot polenta evenly over beef mixture. Sprinkle with remaining parmesan.

6

Grill parmigiana for 5 minutes or until golden. Sprinkle with extra oregano to serve.