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A quick and cozy one-pan casserole combining tender chicken cubes, spinach, and a rich, creamy sauce topped with melted Monterey Jack and Parmesan cheeses, perfect for busy weeknights.

  • Total Time: 30-40 minutes
  • Yield: 4 servings 1x

Ingredients

Scale
  • 3/4 cup mayonnaise (Hellmann’s preferred)
  • 3/4 cup sour cream
  • 1/2 cup freshly grated Parmesan cheese
  • 1/2 teaspoon black pepper
  • 1 teaspoon garlic salt
  • 1/4 teaspoon onion powder
  • 1.25 pounds boneless skinless chicken breast, cut into 1-inch cubes
  • 8 ounces spinach (fresh or frozen, if frozen, fully thawed and squeezed dry)
  • 8 ounces freshly grated Monterey Jack cheese (Tillamook preferred)

Instructions

  1. Preheat oven to 500°F and lightly grease a 9×13-inch baking dish or similar size.
  2. Cut chicken into 1-inch bite-sized cubes, pounding or slicing to an even thickness if needed, and set aside.
  3. Grate Monterey Jack and Parmesan cheeses fresh and measure all ingredients.
  4. If using frozen spinach, thaw completely and squeeze out all excess moisture.
  5. In a medium bowl, whisk together mayonnaise, sour cream, garlic salt, onion powder, and black pepper until smooth. Taste and adjust seasoning if desired.
  6. Spread spinach evenly over the prepared baking dish, breaking up any large clumps.
  7. Scatter chicken cubes evenly on top of the spinach layer.
  8. Pour the creamy sauce over the chicken and gently spread with a spatula to coat evenly.
  9. Sprinkle the grated Monterey Jack and Parmesan cheeses evenly over the top.
  10. Bake on the bottom oven rack at 500°F for 20 to 25 minutes until the cheese is melted, bubbly, and golden brown, or bake at 375°F for 30 to 35 minutes until chicken reaches 165°F internal temperature.
  11. Remove from oven and let rest for 2 to 3 minutes (or 5 to 10 minutes for sauce to fully set) before serving.

Notes

Avoid baking at 500°F for too long to prevent cheese burning and chicken drying out; baking at 375°F longer is recommended for juicier results., Ensure frozen spinach is fully thawed and all excess water is squeezed out to avoid watery casserole., Use evenly sized chicken pieces to ensure even cooking; pounding to about 1 inch thickness or slicing horizontally aids this., Rest casserole after baking so the sauce sets and serving is cleaner and easier., Casserole pairs well with plain rice, buttered egg noodles, green salad with vinaigrette, roasted broccoli or green beans, crusty bread, or soft dinner rolls., Substitutes: rotisserie or turkey for chicken; mozzarella, Colby Jack, or Swiss for Monterey Jack; kale or Swiss chard for spinach; Greek yogurt for mayo and/or sour cream; Pecorino Romano for Parmesan cheese., Add-ins ideas: cooked mushrooms, drained artichoke hearts, or breadcrumb topping mixed with melted butter before baking., Store leftovers in airtight container for up to 4 days refrigerated; can be frozen up to 3 months either baked or unbaked (add 15–20 minutes extra baking if frozen unbaked)., Reheat portions in microwave 2–3 minutes or whole casserole covered at 350°F for 20–25 minutes.

  • Author: Laura
  • Prep Time: 10-15 minutes
  • Cook Time: 20-25 minutes
  • Category: Main Course
  • Cuisine: American

Nutrition

  • Serving Size: 1 serving
  • Calories: Approximately 450 kcal per serving
  • Fat: Around 30 grams per serving
  • Carbohydrates: Approximately 6 grams per serving
  • Protein: About 40 grams per serving