Preheat your oven to 400°F (200°C). Toss the quartered potatoes with 1 tablespoon of olive oil, salt, and pepper on a baking sheet. Roast for 25-30 minutes, flipping halfway, until golden brown and crispy.
While potatoes roast, season the steak cubes evenly with salt, pepper, and Italian seasoning.
Heat the remaining 1 tablespoon of olive oil in a large, heavy-bottomed skillet (cast iron works well) over medium-high heat until shimmering.
Add the steak cubes to the hot skillet in a single layer, ensuring not to overcrowd the pan. Sear for 2-3 minutes per side until browned. Work in batches if necessary to maintain high heat. Remove the steak from the skillet and set aside.
Reduce the heat to medium-low. Add the butter to the same skillet. Once melted, add the minced garlic and cook for about 1 minute until fragrant, being careful not to burn the garlic.
Return the seared steak bites to the skillet. Toss gently to coat the steak completely in the garlic butter sauce. Cook for 1-2 minutes until the steak reaches your desired doneness (about 130°F for medium-rare).
Remove the skillet from the heat. Stir the crispy potatoes into the skillet with the steak bites, tossing briefly to coat them in the remaining garlic butter sauce.
Serve immediately, garnished with fresh parsley and grated Parmesan, if using.
Notes
For the crispiest potatoes, ensure they have space on the baking sheet and do not overlap them during roasting.
To achieve medium-rare steak, use a meat thermometer; remove the steak from the heat when it reaches 125°F, as it will continue to cook while resting in the sauce.
If you prefer a thicker sauce, let the butter and garlic simmer for an extra minute after the garlic is fragrant before adding the steak back in.