Preheat the oven to 350°F (175°C).
In a large skillet, heat the olive oil over medium heat. Add the sliced squash and chopped onion. Sauté for about 10 minutes, or until the squash is tender. Season with salt and black pepper.
In a large mixing bowl, combine the sautéed squash and onion mixture with sour cream, shredded cheddar cheese, beaten eggs, garlic powder, and paprika. Mix well until all ingredients are combined.
Pour the mixture into a greased 9x13-inch baking dish. Spread it evenly.
In a small bowl, mix the crushed crackers with the grated Parmesan cheese. Sprinkle this mixture evenly over the top of the casserole.
Bake in the preheated oven for 30-35 minutes, or until the top is golden brown and bubbly.
Remove from the oven and let cool for about 5 minutes before serving.