Heat oven to 375°F/190°C. Toss steak with 2 tablespoons olive oil, salt, pepper, garlic powder, steak seasoning, Italian seasoning, and paprika. Refrigerate for 15 minutes.
Bring a large pot of water to a boil. Stir in bouillon, add macaroni, and cook until al dente. Drain.
Melt butter in a saucepan over medium heat. Whisk in flour and cook for 2 minutes. Slowly whisk in milk until smooth and thickened, 4 to 6 minutes. Stir in 2 cups cheddar and the mozzarella. Season with garlic powder, seasoned salt, and paprika.
Stir pasta into sauce and transfer to a 9x13-inch/23x33-centimeter baking dish. Sprinkle it with remaining cheddar. Bake for 20 minutes, until golden.
Heat a cast-iron skillet over medium-high. Add 1 tablespoon of olive oil. Sear steak in batches, 2 to 3 minutes per side, until browned. Rest 2 minutes.
Top baked mac and cheese with steak bites and serve hot.