Preheat oven to 350 degrees Fahrenheit.
In a medium bowl, mix the eggs thoroughly. Add water or milk if desired.
Line a small baking dish (mine is 7 x 10) with parchment paper.
Distribute the veggies and spinach or arugula in the dish.
Sprinkle half of the cheese on top of the veggies.
Pour the eggs over the veggie and cheese mixture. Stir lightly with a fork to make sure the eggs get evenly distributed.
Top with remaining cheese.
Bake for approximately an hour, or until the quiche appears set and a knife inserted into the center comes out clean.
Allow to cool and then cut into slices.