Preheat oven to 350°F.
Boil chicken breasts until fully cooked; shred once cooled.
In a large bowl, mix shredded chicken, soup, sour cream, and 2 tbsp poppy seeds.
Spread chicken mixture in a greased 9x13-inch baking dish.
Mix crushed Ritz crackers with melted butter and remaining poppy seeds.
Sprinkle cracker mixture evenly over chicken.
Bake for 35-40 minutes until golden and bubbly.
Let sit for 5 minutes before serving.