Instructions:
- Preheat oven to 375°F (190°C) and grease a 9×13-inch (23x33cm) baking dish with nonstick spray.
- Place onions in a saucepan and add water just to cover.
- Bring to a boil, reduce heat, and let simmer for 8 minutes.
- Drain and toss onion slices with butter.
- In a large bowl, whisk together eggs and evaporated milk.
- Add cooked onions, cracker crumbs, cheese, salt, and pepper.
- Stir to mix.
- Transfer the mixture to the prepared baking dish.
- For the topping, toss together cracker crumbs and melted butter.
- Sprinkle over the casserole.
- Bake until set in the center and the top is golden brown, about 45 minutes.
Notes:
- To make this recipe vegetarian, you can substitute unsalted butter with plant-based butter.
- This casserole can be served as a side dish or a main course for a vegetarian meal.
- If you want to add some more flavors to the dish, you can try adding some diced bacon or ham to the onion mixture before baking.
- This casserole can be made ahead of time and stored in the refrigerator for up to 3 days.
- Just reheat it in the oven at 350°F until heated through.