Preheat oven to 350°.

Prepare potato crust by slicing potatoes to about 1/8th inch thick or so.

Line a 9 inch pie pan or pie plate and with the potato slices with the edges just barely overlapping to create the potato crust.

Bake in the preheated oven for 5 to 10 minutes or until the potatoes just barely start to become crisp, but before they change color or get crispy.

Heat fresh spinach on stovetop in skillet for 2-3 minutes, until wilted.

In medium bowl, whisk together eggs, milk, shredded mozzarella cheese, ricotta cheese.

Add the wilted spinach to the egg mixture.

Pour mixture into the prepared potato crust and bake in the pre-heated oven for 35-45 minutes, or until cooked through.

Remove from oven and cool on wire rack for 15 - 20 to allow quiche to set up.

Serve warm.