Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking dish well to prevent sticking.

Season the chicken breasts with salt and pepper. Cook them in a skillet over medium heat for about 6-7 minutes per side until cooked through. Chop the chicken into bite-sized pieces.

Blanch the broccoli by adding it to boiling water for 3-4 minutes until it turns bright green; then drain it well.

Mix together the cream of mushroom soup, mayonnaise, lemon juice, and half of the cheddar cheese in a bowl until smooth and creamy.

Combine the cooked chicken and blanched broccoli with the creamy sauce, stirring gently to coat all the pieces evenly.

Pour the mixture into the greased baking dish, spreading it out evenly. Top it off with the remaining cheddar cheese and seasoned breadcrumbs.

Bake the casserole in your preheated oven for 25-30 minutes or until it's bubbly and golden brown on top.