Preheat your oven to 190°C (375°F) so it’s fully heated when the casserole goes in. Lightly grease a baking dish with oil or cooking spray, making sure the bottom and sides are coated to prevent sticking and make serving easier.

Cook the chicken using your preferred method (pan-searing, baking, or boiling) until fully cooked through. Season it lightly with salt and pepper while cooking to build flavor early. Once cooked, let it cool slightly, then dice it into bite-sized pieces so it distributes evenly throughout the casserole.

Heat a skillet over medium heat and add a small amount of oil. Add the chopped onion and sauté for a few minutes until it becomes soft and translucent. Stir in the minced garlic and cook for another 20–30 seconds, just until fragrant, being careful not to let it brown.

In a large mixing bowl, combine the Greek yogurt, softened cream cheese, and chicken broth. Add your seasonings and mix until the sauce is completely smooth and creamy, with no visible lumps. This forms the rich, high-protein base of the casserole.

Gently fold the diced chicken and the sautéed onion and garlic into the creamy sauce. Use a spatula and mix slowly to coat everything evenly without breaking up the chicken or making the mixture too thick.

Transfer the mixture into the prepared baking dish and spread it out evenly. Sprinkle the shredded cheese over the top, covering the surface so it melts into a golden, bubbly layer as it bakes.

Place the baking dish in the preheated oven and bake until the casserole is hot throughout, the sauce is bubbling around the edges, and the top is lightly golden. This usually takes about 25–30 minutes.

Remove the casserole from the oven and let it rest for 5–10 minutes before serving. This resting time allows the sauce to thicken slightly and helps the casserole hold together better when spooned onto plates.