Preheat oven to 350 degrees.
Prep veggies: chop broccoli, onion, garlic and mushrooms.
Place broccoli in large stock pot with water and steam until cooked through. (do not overcook)
Season chicken with lemon and pepper seasoning and place in skillet on medium/high heat with minced garlic and oil. Saute' until brown and almost cooked through. (will continue to bake in oven)
In a separate bowl, combine canned soups, sour cream, mayonnaise, lemon juice, onion and garlic powder. Stir until thoroughly combined.
After chicken has browned, dice and set aside.
In a shallow baking dish, layer steamed broccoli in dish, followed by diced lemon and pepper chicken breasts, diced onion, cream mixture and stir.
Bake at 350 for 20 minutes.
While dish is baking, in a small skillet with butter, place crushed Ritz Crackers in skillet and saute' until crispy and brown.
After 20 minutes, top dish with cheddar cheese and Ritz Crackers and bake an additional 10 minutes until cheese is melted and crackers are crispy and brown.
Enjoy!