01 - Bring a large pot of salted water to a boil. Cook the cheese tortellini according to package instructions until tender. 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 crowding. Sear for 2 to 3 minutes per side until a golden-brown crust forms and the steak reaches your preferred doneness. Transfer to a plate and tent loosely with foil.
04 - Reduce the skillet heat to medium. Add the butter and let it melt, scraping up any browned bits from the bottom. Sauté the shallots and minced garlic for about 1 minute until fragrant and softened.
05 - Pour in the heavy cream, stirring to incorporate all the flavors. Bring the mixture to a gentle simmer and cook for 2 to 3 minutes, allowing the sauce to reduce and thicken slightly.
06 - Gradually stir in the grated Parmesan cheese, continuing to stir until fully melted and the sauce is smooth and velvety.
07 - Return the cooked tortellini and seared steak to the skillet. Toss gently to coat everything evenly in the garlic cream sauce. Cook for 1 to 2 minutes until heated through.
08 - Transfer to warm serving plates or a platter. Sprinkle generously with chopped fresh parsley and serve immediately.