1. Preheat your oven to 350°F (175°C). Lightly grease a 9×13-inch baking dish or spray with nonstick cooking spray to prevent sticking.
2. In a large bowl, combine the cream of mushroom soup, sour cream, mayonnaise, Dijon mustard, garlic powder, onion powder, salt, and pepper. Stir until smooth and well mixed. This creamy base is where the magic happens.
3. Add the cooked chicken, diced ham, and 1 ½ cups of shredded Swiss cheese to the sauce mixture. Gently fold everything together until the chicken and ham are evenly coated.
4. Pour the mixture into your prepared baking dish, spreading it out evenly. This is a great moment to sneak a taste of the sauce – it’s a comforting blend of tangy and savory.
5. In a small bowl, mix the crushed crackers or panko with the melted butter until the crumbs are coated. Sprinkle this golden topping evenly over the casserole. This crunchy layer is my favorite part—it adds texture and that irresistible buttery crunch.
6. Bake uncovered for 30-35 minutes, or until the casserole is bubbly and the topping is golden brown. You’ll know it’s done when you see the sauce bubbling at the edges and the crust is nicely toasted.
7. Remove from the oven and let it rest for 5 minutes before serving. This helps the casserole set a bit, making it easier to scoop and enjoy.

One of my mom’s best tips was to never rush letting a casserole rest after baking—it makes all the difference in texture and flavor.