Roast the garlic. Preheat the oven to 400°F (200°C). Slice the top off the garlic head to expose the cloves. Drizzle with a little olive oil, wrap loosely in foil, and roast for 35–40 minutes, or until the cloves are soft and golden. Let cool slightly, then squeeze the roasted cloves from their skins and mash into a smooth paste.
Cook the rigatoni. Bring a large pot of generously salted water to a boil. Cook the rigatoni according to package directions until al dente. Reserve about ½ cup of pasta water before draining.
Prepare the beef. Pat the steak dry with paper towels and season with salt and 1 teaspoon of freshly cracked peppercorns.
Sear the beef. Heat 1 tablespoon olive oil in a large skillet over medium-high heat. Add the steak and sear until deeply browned and cooked to your preferred doneness, about 3–5 minutes per side depending on thickness. Transfer to a plate and rest for 5 minutes before slicing thinly against the grain.
Sauté the shallot. Reduce the heat to medium and add the butter to the same skillet. Add the chopped shallot and cook for 2–3 minutes until softened.
Build the sauce. Stir in the mashed roasted garlic, remaining cracked peppercorns, Dijon mustard, and Italian seasoning. Cook for about 30 seconds until fragrant.
Add the liquids. Pour in the beef broth and scrape up any browned bits from the bottom of the skillet. Stir in the heavy cream and simmer gently for 3–4 minutes until slightly thickened.
Add the Parmesan. Reduce the heat to low and gradually stir in the Parmesan until melted and smooth. If the sauce becomes too thick, add reserved pasta water a little at a time until it reaches a silky consistency.
Combine the pasta and beef. Add the drained rigatoni and sliced beef to the skillet. Toss gently until everything is evenly coated in the creamy peppercorn and roasted garlic sauce.
Serve. Taste and adjust the seasoning as needed. Garnish with fresh parsley, extra Parmesan, and an additional sprinkle of cracked black pepper if desired. Serve immediately while hot and creamy.
