In a large cast-iron skillet, heat 1 tablespoon of olive oil and 1 tablespoon of butter over medium heat. Add the halved baby potatoes, season with half the salt and pepper, and cook for 10-12 minutes until golden and tender. Remove to a plate.
Pat the steak cubes dry with paper towels. Toss with the remaining salt, pepper, garlic powder, and dried thyme until evenly coated.
Increase heat to high and add the remaining olive oil to the skillet. Add the steak bites in a single layer. Sear without moving for 2 minutes to develop a deep golden crust, then flip and cook for 1-2 more minutes.
Reduce heat to medium. Add the remaining 3 tablespoons of butter and the minced garlic to the skillet. Cook for 1 minute until fragrant and foaming, basting the steak bites.
Return the golden potatoes to the skillet and toss everything in the rich garlic butter. Garnish with fresh parsley and serve immediately!