Preheat oven to 350°F. Spray the inside of a 9x13 baking pan with nonstick cooking spray. Set aside.
In a medium mixing bowl, whisk together the soup, sour cream, lemon juice, garlic, salt, and pepper. Fold in the chopped chicken and transfer the mixture to the prepared dish.
10 ounces cream of chicken soup, 1½ cups sour cream, ½ lemon, 1 teaspoon minced garlic, ¼ teaspoon kosher salt, ¼ teaspoon ground black pepper, 4 cups cooked chicken
In a separate bowl, stir together the crushed crackers, melted butter, and poppy seeds. Sprinkle the mixture over the chicken.