To make the dough, combine the flours and salt in a bowl, make a well in the center, and add the lard and olive oil. Working with your fingertips or a pastry cutter, blend in the fats until the mixture resembles coarse crumbs. Sprinkle with 7 tablespoons of the water and toss with a fork until the dough begins to form clumps. If it is too dry, add more water, a teaspoon or so at a time. Gather the dough into a ball, wrap in plastic wrap, and chill for at least 30 minutes.
To make the filling, in a small bowl, combine about ¼ cup of the pancetta with a little of the garlic, about ¼ cup of the onion, and a generous amount of pepper. Set aside.
Cook the remaining pancetta in the olive oil in a large skillet over medium-low heat until it has given off much of its fat, about 5 minutes. Add the remaining onion and cook, covered, for 15 minutes, or until the onion has softened. Uncover, raise the heat to high, and cook until the filling is a rich golden brown, about 6 minutes. Add the spinach, reduce the heat to medium, and cook until the greens are tender, about 7 minutes.
Stir in the remaining garlic and cook for another 30 seconds or so, until fragrant. If a brown glaze has formed on the skillet bottom, add a little water and simmer, scraping the browned bits, until the liquid evaporates. Turn the filling into a bowl and let cool.
Add 1 ¼ cups of the Parmigiano and the reserved pancetta mixture to the filling. Taste for seasoning, and add up to ½ cup more Parmigiano, if desired. Blend in the eggs.
Set a rack as close to the bottom of the oven as possible and preheat the oven to 400 degrees F.
For the garlic oil, combine the lard and garlic in a small pan and heat over medium heat until the lard has melted. Remove from the heat.
Brush a 14-inch pizza pan with the olive oil. Divide the dough in half. On a lightly floured surface, roll out one piece to about a 14-inch circle, and place it on the pan. Spread the filling over the pastry, leaving about a 2-inch border.
Roll out the second piece of dough to a 14-inch round. Dampen the edges of the bottom crust with water, top with the second round of dough, and pinch the edges together. Fold the edges over toward the center of the torta, and crimp. Make a few slashes in the top of the crust for steam to escape.
Bake for 20 minutes. Brush the crust with the garlic oil, and bake for another 20 minutes, or until the top is pale gold and very crisp and the edges are golden brown. Cut into narrow wedges to serve.