Olive Garden’s Copycat Beef Filets In Balsamic Sauce

-A repost
My girlfriend’s parents absolutely love to dine at the Olive Garden. Last week I told Katie to let her parents know that we’d be cooking for them on Friday. Katie and I prepared this simple dish and what a hit it was! We served ours with roasted potatoes and fresh string beans. For sure there were no leftovers! Needless to say, her parents were impressed !
Serves : 6
Ready In : Less than 30 minutes

Ingredients :
6 Beef Tenderloin filets (6 oz size)
4 tablespoons Extra Virgin Olive Oil
4 tablespoons Butter
1 Yellow onion, medium and sliced thin
1 pinch Salt
1 pinch Black pepper
1/2 cup Dry white wine
1/2 cup Marsala wine
1/2 cup Beef broth
2 tablespoons Balsamic vinegar
1 dash Parsley, finely chopped
6 Fresh rosemary sprigs
Directions :
SAUCE: Heat oil and butter in a large saute pan over medium heat. Add sliced onions, salt, and pepper; cook 10 minutes or until softened and golden browned, stir frequently.

Add both wines, broth, vinegar and bring to a boil. Reduce heat and simmer for 10-15 minutes or until sauce is reduced by half.

BEEF: Lightly rub filets with oil; season with salt and pepper. Grill to preferred temperature. Place onions and sauce on a platter and top with steaks. Garnish with parlsey and rosemary.