Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking dish. Set aside. prep

Heat olive oil in a large skillet over medium-high heat. prep

Add chicken cubes to the skillet and season with salt and ¼ teaspoon pepper. Cook, stirring occasionally, until chicken is golden brown and cooked through, about 8-10 minutes. Set aside. prep

Thaw the frozen broccoli according to package instructions. Drain well and pat dry with paper towels to remove excess moisture. prep

In a large mixing bowl, combine the cream of chicken soup, mayonnaise, sour cream, cheddar cheese, milk, lemon juice, garlic powder, onion powder, and the remaining ¼ teaspoon of pepper. Stir to mix evenly. mix

Fold in the cooked chicken and thawed, drained broccoli, ensuring everything is evenly coated. mix

Spread the mixture evenly into the prepared baking dish. assemble

In a small bowl, combine breadcrumbs and melted butter. Stir to coat the breadcrumbs in butter, then sprinkle evenly over the casserole. assemble

Bake for 30 minutes, or until the top is golden brown and the casserole is bubbling around the edges. bake

Let stand for 5 minutes before serving to allow flavors to set. finish