Preheat oven to 350 degrees. Place each chicken breast on a piece of foil large enough to wrap it in. Pound chicken breast with a mallet until evenly flattened. Sprinkle 1/2 tsp lemon pepper and 1/4 tsp pepper on each breast. Place 1/2 C spinach leaves on each breast, sprinkle with 1 Tbsp feta, drizzle with 1/2 tsp olive oil. Starting with the large end, roll the breast, fold foil to keep shape. Prepare sauce, combine ingredients, mix well. Bake in 9×13 baking dish for 35-40 minutes until chicken is no longer pink in the center. Remove foil, pour sauce over chicken, bake an additional 5-10 minutes until sauce is thick and bubbly. Serve!