Heat the oven: Preheat to 375°F (190°C). Lightly grease a 9x13-inch baking dish.

Prep the broccoli: If using fresh, steam or microwave until just tender-crisp. If using frozen, thaw and pat dry. Too much moisture can make the casserole watery.

Cook the bacon: Pan-fry until crisp, then crumble. Reserve a tablespoon of bacon fat if you like for extra flavor.

Make the ranch sauce: In a large bowl, whisk softened cream cheese, sour cream, and heavy cream until smooth. Stir in ranch seasoning, garlic, onion powder, and a pinch of salt and pepper. Taste and adjust seasoning.

Combine the filling: Add cooked chicken, broccoli, and half the crumbled bacon to the bowl. Fold in 1 cup cheddar and 1/2 cup mozzarella until everything is evenly coated.

Assemble: Spread the mixture in the baking dish. Top with remaining cheddar and mozzarella. Sprinkle on the rest of the bacon.

Bake: Bake for 20–25 minutes, until the casserole is hot and the cheese is melted and bubbly. For extra browning, broil 1–2 minutes at the end.

Finish and serve: Let it rest 5 minutes to set. Garnish with sliced green onions or chives. Serve warm.