Plug in waffle iron and heat.
In medium-sized skillet, heat olive oil on medium heat. Sauté mushrooms, leeks and sweet potato until soft. Toss in salt, pepper and spinach and cook until leaves just begin to wilt. Remove from heat and set aside.
Whisk eggs and baking soda in mixing bowl. Add sautéed vegetable mix to egg mixture.
Coat top and bottom of waffle iron with cooking spray. Add ⅓ cup of veggie egg mix to waffle iron. Do not overfill and add just enough to barely cover the bottom grate. Close waffle iron and cook for about two minutes. Remove carefully with fork. Spray waffle iron between each batch.
Serve immediately. Try one with salsa, fresh avocado and goat cheese, or for that savory and sweet combination, butter and maple syrup.