Preheat your oven to 350°F (175°C).

In a large skillet, melt 3 tablespoons of butter over medium heat. Sauté the sliced squash and diced onion until they are soft and lightly golden, about 10–12 minutes. Let the mixture cool slightly.

In a large mixing bowl, combine the sour cream, cream of chicken soup, beaten eggs, shredded cheddar cheese, garlic powder, paprika, salt, and pepper. Mix well.

Stir in the squash and onion mixture until everything is well blended.

Spoon the mixture into a greased 9×13-inch baking dish.

In a small bowl, mix the crushed Ritz crackers with the melted butter. Sprinkle this over the top of the casserole.

Bake in the preheated oven for 30–35 minutes or until the top is golden brown and the casserole is bubbly.

Let it sit for 5 minutes before serving.