1. Preheat broiler.
2. Prepare broccoli in microwave according to package directions.
3. Heat a large ovenproof skillet over medium-high heat. Add oil to pan; swirl to coat. Add onion and mushrooms; cook 12 minutes or until mushrooms brown and liquid evaporates, stirring occasionally. Sprinkle mushroom mixture with flour; cook 1 minute, stirring constantly. Stir in milk. Bring to a boil; cook 3 minutes or until thick and bubbly. Stir in broccoli and chicken; cook 1 minute. Remove pan from heat. Stir in yogurt, mayonnaise, pepper, and salt. Top evenly with cheeses; broil 2 minutes.
MyRecipes is working with Let's Move!, the Partnership for a Healthier America, and USDA's MyPlate to give anyone looking for healthier options access to a trove of recipes that will help them create healthy, tasty plates. For more information about creating a healthy plate, visit www.choosemyplate.gov.