Step 1: Pat the steaks very dry with paper towels. Season generously on all sides with salt and black pepper. Let them rest at room temperature for 30 minutes to 1 hour.
Step 2: Heat a heavy-bottomed cast iron skillet over high heat until it just begins to smoke. Add 1 tablespoon of high smoke point oil.
Step 3: Carefully place the seasoned steaks in the hot skillet. Sear for 2-3 minutes per side for a deep, golden-brown crust. Do not move the steaks during this initial sear.
Step 4: Reduce the heat to medium. Add 2 tablespoons of unsalted butter, rosemary sprigs, thyme sprigs, and 2 cloves of minced garlic to the skillet. Tilt the pan slightly and, using a spoon, continuously baste the melted herb butter over the steaks for another 1-2 minutes.
Step 5: Remove the steaks from the pan and transfer them to a cutting board. Tent loosely with foil and let them rest for at least 5-10 minutes. This is crucial for juicy steaks.
Step 6: While the steaks are resting, drain most of the excess oil from the skillet, leaving about 1-2 tablespoons along with any browned bits (fond). Add the remaining 2 cloves of minced garlic to the skillet and sauté for 30-60 seconds until fragrant, being careful not to burn it.
Step 7: Pour in the heavy cream and bring to a gentle simmer, scraping up any browned bits from the bottom of the pan with a wooden spoon.
Step 8: Stir in the grated Parmesan cheese and a pinch of salt and black pepper. Continue to simmer gently for 2-3 minutes, or until the sauce has thickened to your desired consistency. Taste and adjust seasonings as needed.
Step 9: Slice the rested steaks against the grain into thick pieces. Arrange them on plates and generously spoon the warm creamy garlic sauce over the top. Garnish with fresh parsley or chives, if desired.