Prepare the topping first. Sauté the shallot and garlic in 1 tablespoon olive oil for 5 minutes until softened. Add 2 tablespoons olive oil and sauté the mushrooms over a high heat, stirring frequently. Make sure the mixture is quite dry. Leave to cool. Mix the mushrooms with chopped herbs and season. Whip the cream until softly stiff, and then fold into the mushrooms with the egg yolk. Cover and chill. Season the fillet steaks. Heat a large non-stick frying pan until a strong heat rises. Cook the steaks for 3 minutes, turning them to sear all over. Remove from the pan, season and allow to cool. Peel potatoes, boil in salted water, remove and roast in a baking tray. When ready to serve, heat the oven to 220C and place the steaks in a shallow baking try. Pile the mushroom mixture on top and dust with Parmesan. Cook for 5-7 minutes until the topping is bubbling and golden. Serve with roast potatoes and asparagus.