Bring a pot of salted water to a boil and add halved baby potatoes. Cook for 10-12 minutes until just tender, then drain and set aside.

Season the steak generously with salt and pepper. In a large skillet over medium-high heat, melt 2 tablespoons of butter. Once hot and bubbly, add the steak and sear for about 4-5 minutes per side for medium-rare, adjusting for preferred doneness. Transfer the steak to a plate to rest.

In the same skillet, add the remaining butter, minced garlic, and rosemary. Stir until fragrant, about 30 seconds.

Add the drained potatoes to the skillet and mix well to coat in the garlic butter. Cook for about 5 minutes until they become golden brown.

Slice the steak against the grain and serve on a platter with the golden potatoes, drizzling garlic butter from the skillet over the top. Garnish with fresh parsley if desired.