I used red wine instead of cognac and experienced no problems with "dry beef."
Made this for a valentines dinner with another couple. I have to admit I was a little skeptical about cooking the steaks this way; we are HUGE grillers. The steaks came out perfectly!! The onions were delicious. We served with oven roasted asparagus and a salad-butter lettuce with a blue cheese vinagrette. DELISH! My friend made a flourless chocolate torte with raspberries and fresh whipped cream for dessert which was to die for. Had some onions left over...I think I'm going to make some french onion soup. (the only negative? my house smelled like onions the next day! Out came the candles!)
I made this dish for Valentine's Day dinner. While my husband and I liked the onions, I thought they overpowered the filet, and the sauce was too dry for a cut of meat that has very little fat. I would consider using it on a New York or ribeye steak, but not on a filet. I also did not think it was festive enough for a romantic dinner.
Good recipe. I added sliced fresh mushrooms to the recipe the first time I cooked it, which I would recommend. My second time making it, I still added mushrooms, used 1/2 cup beef broth (no cognac) and also added gorgonzola cheese to the top of each steak during the last 10 minutes it sets out of the oven. It was fabulous!!!