Step 1: Cook pasta shells according to package directions until al dente. Reserve 1 cup of pasta water, then drain the shells and set aside.
Step 2: While pasta cooks, pat the steak pieces dry with paper towels. Season generously with salt, black pepper, garlic powder, and smoked paprika.
Step 3: Heat olive oil in a large skillet or Dutch oven over medium-high heat. Add the seasoned steak and sear for 2-3 minutes per side, until browned and cooked to your desired doneness. Remove steak from the skillet and set aside.
Step 4: Reduce heat to medium. Add butter to the same skillet. Once melted, add minced garlic and cook for 1 minute until fragrant, being careful not to burn it.
Step 5: Add broccoli florets and sliced bell peppers to the skillet. Sauté for 3-5 minutes until vegetables are tender-crisp.
Step 6: Pour in the heavy cream. Bring to a gentle simmer, stirring constantly. Stir in the shredded mozzarella and grated Parmesan cheese until melted and smooth. If the sauce is too thick, add a splash of the reserved pasta water until it reaches your desired consistency.
Step 7: Return the cooked steak and drained pasta shells to the skillet with the sauce. Toss gently to combine, ensuring everything is coated in the creamy sauce.
Step 8: Taste and adjust seasoning with salt and black pepper if needed. Garnish with fresh parsley before serving hot.