I would make everything through step 5. Go ahead and cook the green beans, combine the soup and spices with half of the onions, and bake. Let it cool completely after the 35 minute cooking time. Cover the casserole dish tightly and refrigerate overnight. I like this casserole dish because it has a lid for easy storing and transport. The day you want to serve it, slide the dish back into a 350-degree oven, and heat through for about 20 minutes. You can absolutely slide this casserole next to something else that is already cooking in the oven. It can warm through while other side dishes bake. Finally, add the remaining half of the onions, and bake for another 5-10 minutes until everything is warm, bubbling and crispy on top. Cooking it this way ensures the entire casserole is warmed through, and also keeps the onion topping super crispy. The balance of creamy casserole and crisp onion topping is where the magic is for this recipe.  If you’re making this to bring to someone’s house, save the 10-minute onion crisping step for their house. Just slide the dish into the oven next to anything else they’re warming up.