Preheat your oven to 375°F (190°C).
In a small bowl, mix together the olive oil, Worcestershire sauce, garlic powder, onion powder, dried thyme, and dried rosemary.
Season the London Broil with salt and pepper on both sides.
Rub the herb and oil mixture onto the steak, ensuring it is well-coated.
Place the London Broil in a baking dish and let it marinate for 30 minutes at room temperature.
Once marinated, place the baking dish in the oven and roast for about 50-60 minutes for medium-rare, or until it reaches your desired level of doneness.
While the London Broil is cooking, prepare the blue cheese sauce. In a small saucepan over medium heat, melt the butter.
Add the heavy cream and bring to a gentle simmer.
Stir in the blue cheese crumbles and black pepper, whisking until the cheese is melted and the sauce is smooth. Season with salt to taste.
Once the London Broil is cooked, remove it from the oven and let it rest for 10 minutes before slicing. This will help retain the juices.
Slice the London Broil against the grain into thin strips.
Serve the slices topped with the warm blue cheese sauce.