Step 1Place 1 cup of the flour and the salt in the bowl of a mixer fitted with the paddle attachment. Turn to low speed and add a small handful of the butter at a time. When all the butter has been added, increase speed to medium and mix until the butter is completely blended with the flour. Reduce the speed, add the remaining flour, and mix just to combine. Slowly add the water and mix until incorporated. The dough will come around the paddle and pull cleanly away from the sides of the bowl. It should feel smooth, not sticky.
Step 2Remove the dough from the mixer and check to be certain that there are no pieces of butter remaining; if necessary, return the dough to the mixer and mix briefly again. Pat the dough into a 7- to 8-inch disk and wrap in plastic. Refrigerate for at least 1 hour or up to a day.
Step 3Lightly brush the inside of an 8-by-2-inch-high springform pan with canola oil and place it on a jellyroll pan. Place the dough on a floured surface and rub all sides with flour. Flatten it into a larger circle using a rolling pin or the heel of your hand. Roll out the dough into a circle about one-fourth inch thick and about 14 inches in diameter. (If the dough becomes very soft, refrigerate for a few minutes.)
Step 4To lift the dough into the springform pan, place the rolling pin across the bottom edge and roll it up on the pin. Carefully lower it into the pan, pressing it gently against the sides and into the bottom corners. Trim any that extends more than an inch over the sides and reserve the scraps. Fold the excess dough over against the outside of the ring. (Preparing the tart shell this way will prevent it from shrinking down the sides as it bakes. The excess dough will be removed after the tart is baked.) Carefully check for any cracks or holes in the dough, and patch with the reserved pieces as necessary. Place in the refrigerator or freezer for at least 20 minutes to resolidify the butter. Reserve the remaining dough scraps.
Step 5Set a rack in the middle of the oven and heat to 375 degrees. Line the tart shell with an oiled 16-inch round of parchment paper or aluminum foil. Fill the shell with pie weights or dried beans, gently guiding the weights into the corners of the shell and filling the shell completely. Bake the shell until the edges of the dough are lightly browned but the bottom is still light in color, 35 to 45 minutes.
Step 6Carefully remove the parchment and weights. Check for any cracks or holes and patch with thin pieces of the reserved dough, if necessary. Return the shell to the oven until the bottom is a rich golden brown, 15 to 20 minutes. Remove from the oven and prepare to fill immediately. Once again, check the dough for any cracks or holes, and patch if necessary before filling with the greens mixture. Leave the oven on.
Step 1While the tart shell is baking, heat the olive oil over medium-high heat in the largest saute pan you own. When the oil is hot, begin adding the greens, a couple of handfuls at a time and stir-frying them until they begin to wilt, about 3 minutes. When one batch of green has wilted, add more and continue cooking until all of the greens have been cooked, about 12 to 15 minutes in all. Reduce heat to low, add the green onions and minced garlic and season with 1 teaspoon salt. Cook until the garlic softens and becomes fragrant, about 5 minutes. You will have about 3 to 4 cups of cooked greens.
Step 2Transfer the greens to a food processor and pulse 2 to 3 times to mince. Add the ricotta, goat cheese, half-and-half, one-fourth teaspoon salt, black pepper and nutmeg and pulse until thoroughly mixed. Taste and adjust seasoning. Add the eggs and pulse to combine thoroughly.
Step 3Pour the filling into the baked tart shell. Sprinkle the Parmesan evenly over top. Bake at 375 degrees until the tart is puffed in the center and golden on top, about 1 hour. A knife inserted in the center should come out clean.
Step 4Set the tart aside to cool at least 30 minutes before serving at room temperature. Remove any overhanging dough, using a serrated knife. Gently free the springform pan and remove the outer ring. (This dish can be prepared 1 day ahead, cooled completely, covered tightly with aluminum foil and refrigerated. Reheat in a 350-degree oven before serving.)