01 - Bring a large pot of salted water to a boil. Cook the cheese tortellini according to package directions until tender. Drain through a strainer and set aside.
02 - Pat the sirloin pieces dry and season generously with salt and freshly ground black pepper. Heat olive oil in a large skillet over medium-high heat until shimmering. Add the steak in a single layer and sear for 2 to 3 minutes per side until a deep golden-brown crust forms and the meat reaches your preferred doneness. Transfer the steak to a plate and rest.
03 - Reduce the skillet heat to medium. Add the unsalted butter and let it melt, swirling to coat the pan. Sauté the minced shallots and garlic, stirring frequently, until softened and fragrant, about 1 minute.
04 - Pour in the heavy cream, scraping 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.
05 - Gradually stir in the grated Parmesan cheese, whisking continuously until fully melted and the sauce is silky smooth.
06 - 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. Garnish with chopped fresh parsley and serve immediately.