Heat a saucepan of boiling water with salt and cook the diced potatoes for five minutes. Add the broccoli and cook for a further two minutes. Drain, place in a baking dish and season with salt and pepper.
Heat a heavy frypan until it's very hot. Season the steak with salt and pepper. Cook the steak for two minutes each side and then place on top of the potatoes and broccoli.
Cheese Sauce: Place the double cream in a saucepan and bring to a simmer. Let it reduce and stir in the crumbled cheese. Season and pour the cheese sauce over the steak and potatoes.
Bake in the preheated oven until bubbling, about 20 minutes.