Step 1: Bring a large pot of salted water to a boil over medium-high heat. Add penne and cook al dente according to package directions.

Step 2: Reserve 1 cup of pasta water; drain the rest. Set aside.

Step 1: Season shrimp evenly with blackened seasoning.

Step 2: To a large, 13-inch skillet over medium heat, add oil. Once hot, add shrimp. Cook for 1-2 minutes per side until opaque. Transfer to a plate and tent to keep warm.

Step 1: Season steak evenly with blackened seasoning.

Step 2: Increase heat to high. Add butter to the skillet and allow it to start to melt. Place steak in the skillet. Cook for 1-2 minutes per side, or until browned outside and pink inside. Transfer to the plate with shrimp and tent to keep warm.

Step 1: Reduce heat to medium. Add onions. Cook until softened (3-5 minutes).

Step 2: Add garlic and cook for 1 minute. Add heavy cream, ¼ to ½ cup of pasta water, parmesan cheese, blackened seasoning, salt, and pepper. Stir until the cheese melts and the sauce thickens slightly.

Step 3: Add noodles to the skillet and toss to coat. Add more pasta water as needed to reach the desired consistency.

Step 4: Top the pasta with the cooked shrimp and steak. Garnish with parsley. Serve immediately.