For the crust:

1. Add the salt, black pepper, and grated cheese to the flour and toss.
2. Grate the butter and add to the flour and toss.
3. Beat the egg with 3/4 cup of cold water add to the flour mixture and form into a ball.
4. If the flour mixture is not coming together add a little more water.
5. Refrigerate for about 1 hour or more.

Filling and Assembly:

1. Preheat Oven 350 degrees F.
2. Gently heat a large cast iron pan and add the cup of breadcrumbs.
3. Drizzle the breadcrumbs with the olive oil and toss.  Be sure to watch over the breadcrumbs so that they do not burn but rather become a beautiful golden color.
4. Place the sliced onion in a large bowl and add the capers, toasted breadcrumbs, garlic, basil, and grated Parmesan cheese and toss.
5. Slice the tomatoes to 1/4 inch thickness.
6. Cut the dough in half.
7. Roll out one half of the dough to a 1/4-inch thickness and place in a 9-inch pie dish. Polk the bottom with a fork.
8. Place in the preheated oven for about 10 minutes to gently bake the crust.
9. Remove from the oven and build the pie.
10. Place some onion mixture, followed by the grated mozzarella followed by the tomatoes.  Repeat this process until the ingredients are used up.  Drizzle the pie with one or two tbs. of olive oil.
11. Save a bit of the mozzarella for the top of the pie.
12. Roll out the other half of the dough and lattice the top of the pie.
13. Brush the pie top with the eggwash, followed by the extra mozzarella.
14. Bake for 40-45 minutes until the pie is a beautiful golden color.