01 - Bring a large pot of salted water to a boil. Cook the cheese tortellini according to package instructions until al dente. Drain through a strainer and set aside.
02 - Pat the sirloin pieces dry with paper towels. Season generously on all sides with salt and freshly ground black pepper.
03 - Heat olive oil in a large skillet over medium-high heat until shimmering. Add the steak pieces in a single layer without overcrowding. Sear for 2 to 3 minutes per side until a deep golden-brown crust forms and the steak reaches desired doneness. Transfer to a plate and tent loosely with foil.
04 - Reduce the skillet heat to medium. Add the unsalted butter and let it melt. Sauté the minced shallots and garlic, stirring constantly, until fragrant and softened, about 1 minute.
05 - Pour in the heavy cream, stirring to scrape up any browned bits from the bottom of the skillet. Bring to a gentle simmer and cook for 2 to 3 minutes, allowing the sauce to reduce and thicken slightly.
06 - Stir in the grated Parmesan cheese and continue stirring until fully melted and the sauce is smooth and silky.
07 - Return the cooked tortellini and seared steak to the skillet. Toss gently to coat everything evenly in the garlic cream sauce and heat through for 1 to 2 minutes.
08 - Sprinkle generously with chopped fresh parsley. Serve immediately while hot.