Pat dry your filets and vacuum seal them or use the water displacement method and with ziplock bag (see link above).

Heat up your water bath to 132F (for medium rare steaks).

Carefully drop the steaks in and allow to cook about 1 hour.

Remove the steaks from the sous vide bath and gently pat dry. Season with salt and pepper.

Heat up the butter in a cast iron skillet along with smashed garlic cloves and rosemary sprigs over high heat.

Sear your steaks about 60-90 seconds on each side (remember the steaks are already cooked through, so you just want to sear them quickly). Baste with butter after you flip them.

Let rest 1-2 minutes before serving or slicing.