Melt 4 tablespoons of butter in a medium saucepan over medium heat. Whisk in 4 tablespoons of flour to create a roux, cooking for about 2-3 minutes.

Gradually pour in 2 cups of milk, whisking until the sauce thickens, about 5-7 minutes. Remove from heat and season with salt and pepper.

In a large mixing bowl, combine 3 cups of shredded chicken and 2 cups of sweet corn. Pour the creamy sauce over, stirring until well mixed.

Preheat the oven to 350°F (175°C). Grease a 9x13-inch baking dish and pour in the chicken and corn mixture, spreading evenly.

Crush the Ritz crackers and sprinkle evenly over the casserole.

Bake for 25-30 minutes until golden brown and bubbling. Keep an eye to avoid over-browning.

Let it cool for 5-10 minutes before serving. This allows the sauce to thicken.