Spray a pan with low calorie cooking spray and place over a medium to high heat. Add the diced steak and fry for 5 minutes, until browned.
Remove the steak from the pan and give it another little spray with the low calorie cooking spray. Saute the onions and mushrooms for 3-4 minutes until softened.
Return the meat to the pan along with the black pepper, carrots, stock, and Henderson's Relish.
Bring to the boil, then reduce the heat, cover and allow to simmer gently for 2-2 1/2 hours.
Meanwhile cook the potatoes in a pan of salted water, for around 20 minutes, until they are soft. Drain and mash well, beat the egg and stir through. Keep warm.
When the steak is tender, stir through the cheese spread to make a creamy sauce. Taste and add a little more pepper if you like.
Pre-heat the grill on a high setting.
Pour the creamy steak into an oven proof dish.
Top with the mashed potato and fluff the top with a fork.
Place under the grill for a couple of minutes until the top is golden and crisp.
Serve with your choice of accompaniment.