Step 1 Cut sweet potato into large pieces and place into a saucepan. Cover with cold water and place over high heat. Bring to the boil then simmer for 20 minutes, or until tender. Drain. Add parmesan, table spread and milk and mash until smooth.
Step 2 Place a chargrill pan over medium to high heat. Once the pan is heated, spray steaks with oil. Add steaks to grill pan and cook for 3 minutes on each side for medium rare, or until cooked to your liking. Transfer to a plate and cover to keep warm.
Step 3 Spray mushrooms with oil and add to hot grill pan. Cook for 3–4 minutes on each side, or until browned and tender. Cut each mushroom into slices, then transfer to a plate and cover to keep warm. Return grill pan to heat. Combine stock, Worcestershire sauce, cornflour and pepper. Add to hot pan and stir until mixture comes to the boil. Reduce heat and simmer until sauce has thickened. Pour into a jug.
Step 4 Steam baby spinach for 1 minute, or until just wilted. Spoon mash onto serving plates, top with steak, mushroom slices and spinach, then drizzle with sauce and serve.