You can use a food processor with a grating attachment to grate cheese, potato, and onion in that order (no need to clean in between).  Prepare the filling while the crust bakes.

Crust
2 cups (packed) grated raw potato
1/4 cup grated onion
1/4 tsp salt
1 egg white, lightly beaten
flour for your fingers
a little oil

Filling
1 Tablespoon olive oil or butter
1 cup chopped onion
2 medium cloves garlic, minced
1/2 teaspoon salt
black pepper, to taste
1/2 teaspoon basil
1/4 teaspoon thyme
1 medium cauliflower, in small pieces
2 eggs
1/4 cup milk
1 cup (packed) grated cheddar cheese
paprika

1) Preheat oven to 400, oil a 9-inch pie pan

2) Combine grated potato and onion, salt and egg white in a small bowl and mix well.  Transfer to the pie pan and pat into place with lightly floured fingers, building up the sides into a handsome edge.

3) Bake for 30 minutes, then brush the crust with a little oil and bake it 10 more minutes. Remove from oven, and turn the temperature down to 375.

4) Heat the olive oil or butter in a large skillet.  Add onion, garlic, salt, pepper, and herbs, and saute over midium heat for about 5 minutes. Add cauliflower, stir, and cover.  Cook until tender, stirring occasionally (about 8 to 10 minutes).

5) Spread half the cheese onto the baked crust (ok if it’s still hot). Spoon the sauteed vegetables on top, then sprinkle on the remaining cheese. Beat the eggs and milk together, and pour this over the top.  Dust lightly with paprika.

6) Bake 35 to 40 minutes, or until set.  Serve hot or warm.

– Moosewood Cookbook by Mollie Katzen