Preheat oven to 180 degrees C and place oven rack to middle position.
To make Filling: in a mixing bowl combine Steak Slices and MAGGI Seasoning Sauce and allow to marinate for 5-10 minutes.
Meanwhile Heat Vegetable Oil in a frying pan over medium high heat and sauté Onions, and Peppers until soft and tender. Remove from pan and set aside.
Using the same pan, sauté marinated Beef slices for 3-4 minutes, add Mushrooms and return the Onion and Peppers to the pan. Mix all ingredients and remove from heat.
To make Cheese Sauce: In a large saucepan, melt Butter, add Flour and sauté until flour turns slightly golden.
Add Hot Water, MAGGI Chicken Stock, Cooking Cream, and Swiss Cheese and stir on medium heat until cheese is dissolved. Taking care not to overheat the cream.
Add un-cooked Pasta to the pot and allow pasta to cook halfway.
Pour the half cooked Pasta and sauce mixture into a large round baking dish, gently pack down and spread cooked Meat mixture on top.
Sprinkle grated Mozzarella cheese on top and bake in the oven for 30-40 minutes or until golden on top and the pasta is soft.