Cook the potatoes:
Heat a cast iron skillet over medium-high. Add potatoes and cook for 10–12 minutes, stirring occasionally, until golden. Transfer to a plate.

Season the steak:
Pat 1.5 lbs ribeye steak dry. Rub with 2 tbsp olive oil, then coat with 1.5 tsp salt, 1 tsp pepper, ½ tsp garlic powder, and ½ tsp onion powder.

Sear the steak:
Increase skillet heat to high. Add steak and sear 3–4 minutes per side for medium-rare (135°F internal temperature).

Make garlic butter sauce:
During the last 2 minutes of cooking, add 3 tbsp butter, 5 minced garlic cloves, 1 tbsp parsley, and 1 tsp thyme to the skillet. Spoon melted butter over the steak.

Rest the steak:
Transfer steak to a cutting board. Let rest for 5–10 minutes to retain juices.

Slice and serve:
Slice steak against the grain. Serve with potatoes and drizzle with garlic butter sauce from the skillet.