Pat the beef cubes dry with paper towels and season evenly with salt and black pepper.

Heat oil in a large heavy-bottomed skillet or cast-iron pan over medium-high heat until shimmering.

Place steak bites in the pan in a single layer, ensuring they do not touch. Sear for 2 minutes per side until a deep brown crust forms. Remove steak from pan and set aside on a plate.

Lower the heat to medium and add butter to the same pan. Once melted, add the minced garlic and sauté for 60 seconds until fragrant.

Deglaze the pan by pouring in the heavy cream, using a spatula to scrape up the browned bits (fond) from the bottom.

Simmer the cream for 2 minutes, then whisk in the Parmesan cheese until the sauce thickens and reaches a smooth consistency.

Add the steak bites and any accumulated juices back into the skillet. Toss to coat thoroughly in the sauce for 1 minute.

Garnish with chopped parsley and optional red pepper flakes before serving.