Begin by preheating your oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish and set aside.
Cook the Broccoli:
Steam the chopped broccoli for about 10 minutes, or until it becomes fork-tender. Drain and let it cool slightly.
Mix the Casserole Base:
In a large mixing bowl, combine 2 cups of shredded cooked chicken breast, 2 eggs, 1 cup of grated cheddar cheese, 1 cup of mayonnaise, and 1 can (10 ounces) of cream of mushroom soup. Stir until everything is well mixed.
Add the Vegetables:
Fold in the steamed broccoli and 1 cup of thawed peas. Mix gently until the vegetables are evenly distributed throughout the mixture.
Assemble and Bake:
Pour the mixture into the prepared baking dish and spread it out evenly. Bake in the preheated oven for 30 to 35 minutes, or until the top is golden and the casserole is heated through.
Cool and Serve:
Allow the casserole to cool for a few minutes before serving to help it set. Serve warm and enjoy!