Preheat the oven to 325°F (163°C).

Heat a large oven-safe skillet or cast-iron pan over medium-high heat.

Melt 2 tablespoons of butter.

Add the halved baby potatoes, onion powder, ¼ teaspoon salt, and black pepper.

Toss well and arrange the potatoes cut-side down in a single layer.

Cook undisturbed for 2 minutes until lightly browned.

Continue cooking for another 4 minutes, stirring occasionally, until the potatoes begin to soften.

Transfer the potatoes to a baking sheet and place them in the oven while preparing the steak.

Carefully wipe out the skillet.

Melt the remaining 1 tablespoon butter over medium-high heat.

Add the steak cubes in a single layer and season with the remaining kosher salt.

Sear the steak for 4–5 minutes, turning occasionally, until browned on all sides and cooked to your preferred doneness.

Reduce the heat to low.

Add the remaining tablespoon of butter, minced garlic, and fresh thyme.

Stir continuously for about one minute until fragrant.

Remove the potatoes from the oven and add them to the skillet.

Toss everything together until coated in the garlic butter sauce.

Sprinkle with chopped fresh parsley before serving.