Slice all your onions. In a large pot, melt your butter and add onions, shallots, soy sauce, brown sugar, garlic salt, red pepper flakes, black pepper, and thyme. Saute on medium for about an hour, stirring occasionally or until onions are deep brown in color and caramelized. Now add your thinly sliced steak and garlic. Saute until steak is cooked. Set aside. Preheat oven to 400°. Boil water. Once boiling, add salt, and cook pasta, reducing cooking time by a third (to prevent overcooking in oven). Remove thyme bundle if in your beef onion mixture. Add cooked pasta to beef and onion mixture along with can of evaporated milk. Stir everything until well combined. Spray a 13x9 with non-stick spray and pour in pasta mixture. Top with grated gruyere and provolone. Cover with a piece of foil and bake in oven for 20-25 minutes until cheese is all melted and pasta is bubbling. Remove from oven, let set for 5 minutes and then serve immediately. Enjoy!