Step 1: Cook the spaghetti according to package directions in a large pot of salted water until al dente. Drain, reserving ½ cup of the pasta water, and set aside.
Step 2: Season the steak bites generously with salt, black pepper, and garlic powder.
Step 3: Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Add the seasoned steak bites and sear for 1-2 minutes per side until beautifully browned and cooked to your desired doneness. Remove the steak from the skillet and set aside.
Step 4: In the same skillet, melt 4 tablespoons of unsalted butter over medium heat. Add the 3 minced garlic cloves and sauté for 1 minute until fragrant.
Step 5: Pour in 1 cup of heavy cream, then stir in ½ cup of grated Parmesan cheese, ½ tsp of Italian seasoning, and ½ tsp of red pepper flakes if you're using them for a touch of heat. Bring the sauce to a gentle simmer, stirring constantly, and cook for 2-3 minutes until it thickens and becomes smooth and creamy.
Step 6: Stir the 1 cup of sliced roasted red peppers into the creamy Alfredo sauce.
Step 7: Add the cooked spaghetti and the seared steak bites back into the skillet with the sauce. Toss everything gently to coat the pasta and steak evenly. If the sauce seems too thick, add a little of the reserved pasta water, one tablespoon at a time, until you reach your desired creaminess.
Step 8: Garnish with 1 tablespoon of fresh chopped parsley before serving immediately.