Cook the macaroni according to package instructions.
In a large skillet, heat olive oil over medium heat.
Add the diced onions and green bell peppers to the skillet, sautéing until soft.
Stir in the minced garlic and cook for another minute.
Increase the heat and add flank steak to the skillet, cooking until browned.
In a large bowl, combine the cooked macaroni with the beef and vegetable mixture.
Add in the cheddar cheese, cream cheese, Worcestershire sauce, black pepper, and salt.
Pour in the milk to reach the desired creamy consistency and mix well.
Transfer the mixture to a baking dish and spread evenly.
Top with additional cheddar cheese, if desired.
Bake in a preheated oven at 350°F for about 20-25 minutes, until the cheese is bubbly.
Remove from the oven and let it rest for a few minutes before serving.