Step 1
Preheat your grill to medium-high heat.
Step 2
Season the steaks generously with salt and black pepper on both sides.
Step 3
Brush the steaks with olive oil and grill for about 4-5 minutes on each side for medium-rare, or until they reach your desired level of doneness. Transfer to a plate and cover with foil to keep warm.
Step 4
In a large pan, heat the remaining olive oil over medium-high heat. Add the minced garlic and cook for 1-2 minutes until fragrant. Add the sliced mushrooms and cook for about 5-7 minutes, or until they release their liquid and become golden brown.
Step 5
Add the beef stock to the pan and stir well. Simmer for about 5-7 minutes, or until the liquid is reduced by half.
Step 6
Add the heavy cream, grated Parmesan cheese, chopped parsley, and chopped rosemary to the skillet and stir well. Simmer for 2-3 minutes, or until the sauce is thick and creamy.
Step 7
Season the mushroom sauce with salt and black pepper to taste.
Step 8
Serve the grilled tenderloin steaks hot with mushroom sauce on top.