Preheat oven to 350 degrees

Melt 2 tablespoons butter in large skillet over medium-low heat. Add onions and cook until tender.

Once the onions are close to being done, add the squash to the pan and cook for 1 min. Add the remaining 2 Tbsp butter and melt. Do not overcook the squash. It should still be fairly raw.

In a large bowl, add eggs and lightly whisk. Add cheese, milk, cayenne pepper, salt and regular pepper and whisk into egg until well combined. Add cooked squash and onions to egg mixture and stir well to combined.

Spray a 8x11 casserole dish with cooking spray and pour squash casserole mixture into the baking dish. Top evenly with crushed Ritz crackers. Place in preheated oven and bake 45 minutes, or until top has lightly browned and casserole does not “jiggle” when the dish is moved.

Allow to sit for about 3 minutes before serving.