Prepare the steak. Pat the steak cubes dry with paper towels. In a small bowl, combine the smoked paprika, garlic powder, onion powder, oregano, thyme, cayenne pepper, salt, and black pepper. Toss the steak bites thoroughly with the seasoning mixture.
Cook the pasta. Bring a large pot of salted water to a boil and cook the fettuccine according to package directions until al dente. Reserve about ½ cup of pasta water before draining.
Sear the steak bites. Heat the olive oil in a large heavy skillet over medium-high to high heat. Add the steak in a single layer, working in batches if necessary. Sear for about 2 minutes per side, or until deeply browned and cooked to your preferred doneness.
Finish with butter. Reduce the heat slightly and add 2 tablespoons of butter to the skillet. Toss the steak bites in the melted butter for about 30 seconds, then transfer them to a plate and let them rest.
Start the Alfredo sauce. In a separate large skillet or the same skillet after carefully wiping away excess burnt spices, melt 4 tablespoons of butter over medium-low heat. Add the minced garlic and cook for about 30 seconds until fragrant.
Add the cream. Pour in the heavy cream and bring it to a gentle simmer. Cook for 3 to 4 minutes, stirring occasionally. Avoid letting the sauce boil rapidly.
Add the Parmesan. Reduce the heat to low and gradually stir in the freshly grated Parmesan cheese until melted and smooth. Season with salt and black pepper.
Combine with pasta. Add the drained fettuccine to the Alfredo sauce and toss until every strand is evenly coated. If the sauce is too thick, add reserved pasta water a little at a time.
Add the steak bites. Arrange the blackened steak bites over the creamy fettuccine or gently toss some of them directly into the pasta.
Serve immediately. Garnish with fresh parsley and additional Parmesan, if desired. Serve hot while the Alfredo sauce is at its creamiest.