Preheat oven to 375⁰ F.
In a saute pan over medium heat add olive oil, and onions. Saute for about 3-4 minutes, and then add garlic and saute until lightly browned.
Add mushrooms, saute for 1 minute, and then add tomatoes. Mix together and cook for 1-2 minutes. Add spinach and 2 tablespoons of water and cover for 2-3 minutes until spinach is wilted. Set aside when done.
Whisk eggs, 1/3 cup water or milk, nutritional yeast, Dijon mustard, red pepper flakes, and sea salt together in a medium size bowl and set aside.
Oil a 9″ pie pan. Place veggie mixture into the bottom of the pan and spread evenly. Pour egg mixture over veggies, make sure you leave about 1/2″ of space under the lip of the pan. Sprinkle paprika over the top, if desired. Cook for 30 minutes or until set and lightly browned on the top.