Pre-heat oven to 375 degrees F
In a large bowl, mix eggs, milk, and pepper.
Sprinkle tuna, 3/4 cup cheese and 1/2 cup spinach into each pie crust.
Pour egg mixture over it (do not overfill). About 1 1/2 cups per crust
Sprinkle remaining cheese on top of egg mixture.
Bake for 40 minutes until center is completely set.
Let cool before slicing and serving.