Preheat your oven to 350°F. Grease a large casserole or au gratin dish.
Cook your bacon to your desired crispiness, and safely drain all but 1 tablespoon of the bacon grease from the pan.
Add your onions in to the pan, and cook in the bacon grease until they're soft and start to brown.
Stir in your spinach, and cook just until it's wilted. Salt and pepper to your taste and remove from the heat.
Add your potatoes and veggies in to your prepared baking dish. Give it a little mix and spread it evenly on the bottom of the pan. Crumble the bacon evenly over the mixture.
Whisk your eggs and water (or milk) in a medium sized bowl. Season with salt and pepper and pour evenly over your vegetables in the baking pan.
Bake your casserole for about 30 minutes, until the middle is cooked through. Serve hot.
Leftovers will keep in the refrigerator for 4-5 days.