Preheat the oven: Set to 375°F (190°C). Lightly grease a 9x13-inch casserole dish with olive oil spray.
Cook the bacon: In a skillet over medium heat, cook bacon until crisp.
Drain on paper towels and crumble. Reserve 1 tablespoon bacon fat in the skillet.
Sauté aromatics: Add onion to the skillet with bacon fat. Cook 3–4 minutes until soft.
Stir in garlic for 30 seconds until fragrant. Remove from heat.
Prep the broccoli: Steam or blanch broccoli for 2–3 minutes until bright green and just tender. Drain well to avoid a watery casserole.
Make the sauce: In a large bowl, whisk cream cheese, Greek yogurt, cottage cheese (if using), and chicken broth until smooth.
Stir in ranch seasoning, smoked paprika, and black pepper.
Combine the filling: Fold in cooked chicken, sautéed onion and garlic, half the crumbled bacon, 1/2 cup cheddar, and all the mozzarella. Gently mix in broccoli.
Assemble: Spread the mixture evenly in the prepared casserole dish. Top with the remaining 1/2 cup cheddar and the rest of the bacon.
Bake: Cover loosely with foil and bake for 15 minutes.
Remove foil and bake another 10–12 minutes until bubbly and lightly golden at the edges.
Finish and serve: Let rest 5 minutes. Garnish with chives or green onions. Serve on its own or over rice, cauliflower rice, or roasted potatoes.