In a large pot, bring salted water to a rolling boil. Carefully add the penne pasta and cook according to the package instructions until al dente. Once cooked, reserve 1/2 cup of the starchy pasta water before draining the penne. Set the drained pasta aside.
Heat a large skillet over medium-high heat and melt 2 tablespoons of butter. Add the thinly sliced beef, seasoning it generously with salt and black pepper. Sauté the beef until it is browned and cooked through, about 3-4 minutes. Once cooked, remove the beef from the skillet and set it aside on a plate.
In the same skillet, reduce the heat to medium and add the remaining 2 tablespoons of butter. When the butter has melted and started to foam, add the minced garlic. Sauté the garlic for about 30 seconds or until it becomes fragrant and lightly golden, taking care not to burn it.
Stir in the dried oregano and, if desired, the red pepper flakes. Allow the mixture to cook for an additional minute to combine the flavors.
Next, add the reserved cooked penne along with the reserved pasta water to the skillet. Toss everything together gently, ensuring that the penne is evenly coated in the garlic butter sauce.
Return the previously cooked beef to the skillet, mixing well to combine all ingredients. Allow the mixture to cook for an additional 1-2 minutes, just to warm the beef through. Taste and adjust seasoning with additional salt and freshly ground black pepper as needed.
Once ready, remove the skillet from heat. Garnish the dish with finely chopped parsley and serve immediately, topped with a generous sprinkle of grated Parmesan cheese.
Notes
Serve the penne in individual bowls, emphasizing the garnished herbs and cheese to create an inviting look. A drizzle of high-quality olive oil can also add a touch of elegance.