Preheat oven to 400. Thaw spinach and corn, if frozen.
1. Grease a 9" pie pan with 1 tsp. oil.
2. Grate both cheeses and combine them.
3. Shred potatoes and onions. (We suggest not using frozen hashbrowns, because they don't hold together as well.)
4. Mix shredded potatoes and onions with cornstarch, salt, and pepper,
then fry into a 10" round, cooking until bottom is golden.
4. Invert hashbrown crust into pie pan. (That's soft side down.)
6. Brown mushrooms in a skillet, with 1 Tbsp olive oil and 2 tsp minced
garlic. Add spinach, corn, and sliced olives. Salt to taste. Cook until
spinach is warmed through.
7. Spoon half of vegetable mixture into pie pan. Top with half of cheese. Repeat with other halves.
8. Whisk together eggs, milk, 1/4tsp salt, 1/4tsp pepper. Pour mixture into pie pan and bake 20-25 minutes, until set.