Preheat oven to 350 degrees Fahrenheit. Spray a 9×13 inch casserole dish with non-stick spray and set aside.: As the oven warms, you should feel a steady heat from the dial and hear the oven click as it cycles on, creating an even baking environment that will brown the topping consistently. Proper preheating ensures the casserole starts cooking immediately and helps the topping crisp rather than steam. A common mistake is sliding the dish into an oven that has not fully preheated, which can result in underbaked filling and a soggy top.
Boil raw chicken breasts for 20 minutes. Let chicken cool slightly and cut into one inch cubes. Place cubed chicken in prepared casserole dish.: When the water reaches a gentle boil you will see steady rising bubbles and a faint steam scent, which signals the meat is cooking through. Proper boiling produces tender, fully cooked chicken that shreds easily yet retains moisture. After simmering, there is often an audible faint pop as the liquid cools off the meat, and the surface will look opaque and firm. A typical error is over boiling, which causes dry, stringy pieces, so check the chicken for doneness and avoid extended high rolling boils.
In a bowl stir together 2 cans of condensed soup and sour cream. Add the Worcestershire sauce, celery salt, garlic, lemon juice, and pepper to the soup and sour cream mixture. Pour sauce over the chicken.: Combining these ingredients creates a glossy, thick sauce with a rich scent of savory soup and bright lemon. As you whisk, notice a slight resistance and smooth texture signaling the components are fully integrated. Pouring this sauce over the cubed chicken ensures each piece is coated, and the aroma of garlic and Worcestershire will begin to perfume the pan. Don’t skip tasting for seasoning—an oversight here can leave the finished casserole under seasoned.
In a separate bowl, stir together the crushed crackers, poppy seeds and melted butter. Sprinkle over the chicken and sauce.: The crushed crumbs should glisten slightly from the melted butter , and the small black flecks of poppy seeds will stand out visually. Mixing until the crumbs are evenly moist prevents clumping and ensures the topping spreads uniformly. When you sprinkle it across the sauce, aim for an even layer so that browning is consistent. A common pitfall is adding too little butter , which can leave the topping dry and pale instead of golden and crisp.
Bake for 30 minutes in the preheated oven at 350 degrees Fahrenheit, until the top of the casserole is browned and the sauce is bubbly. Serve plain or over rice or egg noodles.: During baking you will notice a gentle bubbling along the edges, and the topping will transition from pale to golden, then to a deeper brown in spots, producing a toasty aroma. The bubbling indicates the sauce has heated through and thickened, while the browned crumbs signal a satisfying crunch. Allowing the casserole to rest for a few minutes after removing it prevents the sauce from running and makes serving neater. A common mistake is pulling the dish out too early, which leaves the center underheated and the topping soft rather than crisp.