Preheat your oven to 350°F (175°C).

For the best flavor, season the cubed chicken breast generously with kosher salt and allow it to rest at room temperature for at least 20 minutes while preparing the remaining ingredients.

Place the drained artichoke hearts in a clean kitchen towel, paper towel, or cheesecloth and squeeze out as much liquid as possible. Finely chop and set aside.

Using the same towel, squeeze excess moisture from the thawed spinach. Removing extra liquid helps create the perfect casserole texture.

Heat a large skillet over medium heat. Add the oil and swirl to coat.

Add the chicken pieces in a single layer. Season lightly with black pepper and cook for 2–3 minutes. Flip and continue cooking for another 2–3 minutes until mostly cooked through. Remove from heat and drain any excess liquid if necessary.

In a small food processor, combine the cottage cheese, garlic cloves, kosher salt, black pepper, and onion powder. Blend until completely smooth and creamy.

In a large baking dish, combine the cooked chicken, chopped spinach, chopped artichokes, blended cottage cheese mixture, and approximately two-thirds of the mozzarella and Parmesan cheeses.

Stir everything together until evenly combined and spread into an even layer.

Cover the dish tightly with foil and bake for 20 minutes.

Remove the foil and sprinkle the remaining mozzarella and Parmesan evenly over the top.

Return the High-Protein Spinach and Artichoke Chicken Casserole to the oven and bake uncovered for an additional 10 minutes.

For a golden, bubbly finish, switch the oven to broil for 2–3 minutes, watching carefully to prevent burning.

Let rest for 5 minutes before serving.