Preheat and prep veggies. Preheat oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish. Steam or briefly blanch broccoli for 2 minutes until bright green; drain.
Saute aromatics. In a large skillet over medium heat, warm olive oil. Add onion and cook 3–4 minutes until soft, then add garlic and cook another 30 seconds until fragrant.
Combine base ingredients. In a large bowl, mix shredded chicken, chopped bacon, broccoli, spinach, and the sautéed onion/garlic mixture.
Make creamy sauce. In a smaller bowl, whisk together Greek yogurt, cream cheese, chicken broth, Dijon mustard, smoked paprika, salt and pepper until smooth.
Build the casserole. Pour sauce over the chicken-veggie mix and stir to evenly coat. Transfer everything into the prepared baking dish and spread flat.
Add the cheese topping. Sprinkle shredded cheddar evenly over the top.
Bake. Place the dish in the preheated oven and bake for 25-30 minutes, or until the cheese is melted and bubbly and the edges are slightly golden.
Garnish & serve. Remove from oven, let rest 5 minutes. Sprinkle chopped parsley, slice into 8 pieces, and serve warm.
