Sprinkle chicken tenderloins with 1 teaspoon of chopped rosemary and salt and pepper on both sides. Place olive oil in skillet and heat up to medium heat and cook chicken tenderloins about 3-4 minutes per side or until juices run clear. Remove chicken from pan and keep warm. (DO NOT WASH THE PAN)
Add the sliced onions to the pan and add 1 teaspoon of rosemary and salt and pepper to taste. Saute onions until slightly golden brown but still have a nice little aldente crunch about 5-8 minutes. Remove onions from the pan and keep warm.
Add white to pan and deglaze pan for about 2 minutes to allow the alcohol to burn off. Add the chicken broth to the wine sauce and allow to reduce sauce to reduce by half. Check and adjust seasoning. Add the cooked chicken and onion back to pan to rewarm and then add margarine/butter to the pan and remove from the heat. Stir to melt the margarine/butter.
Serve Rosemary Chicken with Caramelized Onion Sauce on a plate with chicken on the bottom mounded on top with onions and drizzled on top with the wine sauce. Enjoy!
Leftovers can be refrigerated in a sealed container up to 3 days or frozen up to 2 months.