Place the roast on a paper towel-lined plate. Allow the roast to come up to room temperature, about 1 hour.
Pat the roast dry on all sides with paper towels. Sprinkle generously with salt and pepper.
Place a cast-iron skillet over high heat. Add the oil and heat until shimmering. Carefully lay the roast in the hot oil, being mindful that the oil may pop. Sear the roast until evenly browned and deeply seared on all sides, about 3 minutes per side. Turn off the heat and pour 1 cup beef stock into the skillet. Add the garlic cloves and surround the roast with the rosemary and thyme.
Transfer the skillet to the oven and roast, 45 to 60 minutes, depending on the desired doneness (for medium and a bright pink center, cook until an instant-read thermometer inserted in the center of the roast registers 130 degrees F, about 50 minutes). Transfer the roast to a cutting board. Discard the garlic cloves and herbs. Tent the roast with aluminum foil while creating the pan sauce.
Place the skillet back on the stove over medium-high heat. Add the shallots, red wine and remaining 1/2 cup beef stock and simmer, stirring occasionally, until the shallots have softened and the liquid has reduced in volume by half, about 5 minutes. Stir in the brandy, heavy cream and mustard and cook just until a thin sauce comes together, about 2 minutes more.
Slice the rested roast thinly and place on a serving platter. Serve warm with a drizzle of the sauce and a sprinkle of fresh parsley.