Melt your butter in a medium sized saucepan and add your flour. Cook out for 1 minute until it starts to smell biscuity, then gradually add your milk in small increments until it is fully incorporated into a smooth sauce. Bring to a boil, the simmer for 1 minute more until the sauce thickens.
Turn your sauce off the heat and add your provolone, cheddar and mozzarella along with your seasoning. Stir to combine, then add your cooked macaroni. Mix until the pasta is totally coated in the sauce.
Spoon your macaroni onto a lined tray to form two sub roll shapes and chill in the freezer for around an hour, by which point the pasta should have firmed up totally.
Heat a large frying pan on a high heat. Add 1 tbsp vegetable oil, then fry your sliced steak along with onion granules, salt and pepper, for about 2 mins until the outside is starting to caramelise. Remove from the pan, then add a little more oil. Fry your peppers and onions in the pan for about 5 mins, until they are soft and starting to caramelise. Set aside.
Dip your rolls in your flour, egg and panko breadcrumbs in turn.
Fill a large sturdy pan 1/3rd of the way with vegetable oil and heat to 180°C. Gently lower your buns in in turn, and fry for about 3 mins until they are totally crisp and golden. Set aside.
Lay your steak, peppers and onions on top of the base of your baguette. Top with provolone, then grill for 2 mins until the cheese has melted. Place the top of the baguette on top and serve immediately!