01 - Bring a large pot of salted water to a boil. Cook the cheese tortellini according to package instructions until tender. Drain thoroughly 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, working in batches if needed. Sear for 2–3 minutes per side until a deep golden-brown crust forms and the steak reaches your preferred doneness. Transfer the steak to a plate and tent loosely with foil.
04 - Reduce the skillet heat to medium. Add the butter and let it melt. Sauté the shallots and minced garlic, stirring frequently, until softened and fragrant, about 1 minute. Avoid browning the garlic.
05 - Pour the heavy cream into the skillet, scraping up any browned bits from the bottom. Bring to a gentle simmer and cook for 2–3 minutes, stirring occasionally, until the sauce thickens enough to coat the back of a spoon.
06 - Gradually stir in the grated Parmesan cheese, continuing to stir until fully melted and the sauce is silky smooth.
07 - Return the cooked tortellini and seared steak to the skillet. Toss gently until everything is evenly coated in the garlic cream sauce and heated through, about 1–2 minutes. Taste and adjust seasoning as needed.
08 - Transfer to warm plates or a serving dish. Sprinkle generously with chopped fresh parsley and serve immediately.