01 - Pat the sirloin pieces dry and season generously on all sides with salt and freshly ground black pepper.
02 - Heat 1 tablespoon of olive oil in a large skillet over medium-high heat until shimmering. Arrange the steak pieces in a single layer without crowding 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 set aside.
03 - Reduce the heat to medium. Add the remaining tablespoon of olive oil and the butter to the same skillet. Once the butter has melted and begun to foam, stir in the minced garlic and sauté for about 1 minute until fragrant, taking care not to let it brown.
04 - Pour the heavy cream into the skillet and bring to a gentle simmer, stirring occasionally. Gradually whisk in the grated Parmesan cheese and continue stirring until the sauce is smooth and slightly thickened, approximately 2 minutes.
05 - While the sauce simmers, cook the cheese tortellini in a large pot of generously salted boiling water according to the package directions. Drain thoroughly in a colander.
06 - Add the drained tortellini to the garlic cream sauce, tossing gently to coat each piece evenly. Return the seared steak and any accumulated juices to the skillet and fold everything together. Cook for 1 to 2 minutes over low heat, allowing the flavors to meld.
07 - Transfer to warm plates, garnish with freshly chopped parsley and an extra sprinkle of Parmesan if desired, and serve immediately.