Preheat the oven: Set your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish with cooking spray or a drizzle of olive oil.
Season the chicken: Pat the chicken dry and toss with salt, pepper, garlic powder, and onion powder. Spread it in an even layer in the prepared baking dish.
Make the creamy base: In a bowl, whisk together the softened cream cheese, Greek yogurt, ranch seasoning, and chicken broth until smooth.
If it seems too thick, add a splash more broth.
Combine with cheese: Stir in 1/2 cup of the cheddar and the mozzarella (if using). Fold in half of the bacon and half of the green onions.
Add optional veggies: If using broccoli or peas, scatter them over the chicken. This adds fiber and keeps the dish balanced.
Assemble the bake: Pour the creamy mixture over the chicken and veggies, spreading it evenly.
Top with the remaining 1/2 cup cheddar.
Bake: Cover the dish with foil and bake for 20 minutes. Remove the foil and bake another 10–15 minutes, until the chicken is cooked through (165°F/74°C) and the top is bubbly and lightly browned.
Finish and serve: Sprinkle with the remaining bacon and green onions. Let it rest for 5 minutes, then serve as-is or over cauliflower rice, brown rice, or a side salad.