Press pie crust into the bottom and up the sides of a 9-inch, removable-bottom tart pan (or 9-inch pie pan). Set aside.
In a large bowl, combine spinach, stir-fried vegetables and place on top of uncooked crust. In another bowl combine ricotta, cheddar, milk, eggs, Dijon, oregano, salt, and black pepper. Mix well. Spoon cheese mixture on top of vegetable mixture in prepared pie crust and top with Parmesan.
Bake 20 minutes, until a knife inserted near the center comes out clean and crust is golden brown.