01 - Bring a large pot of salted water to a boil. Cook the cheese tortellini according to package directions until tender and floating. 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 until foaming. Stir in the chopped shallots and minced garlic, cooking for about 1 minute until fragrant and softened, being careful not to let the garlic brown.
04 - Pour the heavy cream into the skillet, stirring to scrape up any browned bits from the bottom. Bring the mixture to a gentle simmer and cook for 2 to 3 minutes, allowing the sauce to reduce and thicken slightly.
05 - Stir the grated Parmesan cheese into the simmering cream sauce, stirring continuously until the cheese is fully melted and the sauce is smooth and velvety.
06 - Return the drained tortellini and seared steak to the skillet. Toss gently to coat everything evenly in the garlic cream sauce and warm through for 1 to 2 minutes. Sprinkle with chopped fresh parsley and serve immediately.