Spinach Quiche

For the Crust:
In a large bowl, mix together the flour, sugar, and salt. Add in the cubed butter and toss with a spatula to coat the butter in the flour. 
Using a pastry cutter, work the butter into the flour until the mixture is a coarse meal. The butter should be about the size of peas. 
Using a silicone spatula, slowly blend in just enough ice water to form moist clumps. 
Pour the shaggy dough out onto a clean surface and knead it gently, until it comes together in a ball, adding more ice water only if absolutely needed. 
Form the dough into a neat ball and gently flatten into a disk. 
Wrap the disk in plastic wrap and place in the refrigerator to chill for at least 1 hour, or up to 48 hours.

How to Roll Out the Crust:
Remove the crust from the refrigerator and let it rest for 15 minutes. Lightly flour a rolling pin and a large clean work surface. 
Set the dough in the middle of the work surface and – beginning from the center of the disc – roll the dough away from you in one firm and even stroke. After each stroke, rotate the disc a quarter turn clockwise and roll again. Lightly sprinkle more flour on the work surface, pie dough, and rolling pin as needed. You want to use just enough to prevent the dough from sticking. As your disc of dough becomes larger, be sure not to overstretch the center of the dough. Continue rolling until the dough is about 16-inches in diameter, and around a 1/4" in thickness.
Press the crust into a 10" tart or pie pan, firmly pressing it into the bottom and ridges. 
Trim excess dough, leaving a ¼” of overhang. Roll the overhand underneath the rim of the pie plate and crimp. Refrigerate for 20 minutes. 

How to Blind Bake the Crust:
Preheat the oven to 375 degrees (F). Remove the crust from the fridge. Line the crust with parchment paper and fill with pie weights or dry beans.
Bake in the lower third of the oven for 20 minutes. Remove from the oven. Carefully remove the pie weights and parchment paper and prick the bottom of the crust all over with a fork.
Place back in the oven and bake for 15 more minutes. Set aside until needed. Reduce the oven temperature to 350 degrees (F). 

How to Make the Quiche:
Place the frozen spinach in a large skillet or saucepan and cook over medium heat, stirring occasionally, until thawed, about 3 to 5 minutes. Remove pan from heat and drain spinach in a fine mesh strainer, removing as much excess liquid as possible. Set aside until needed.
Place the skillet back on the stovetop over medium heat. Add the olive oil and white onion and cook, stirring occasionally, until the onion has softened and is becoming translucent, about 6 to 8 minutes. Do not let the onion brown. Transfer the cooked onion to a small bowl and set aside until needed.
In a large bowl whisk together the eggs, heavy cream, cornstarch, salt, cayenne pepper, and nutmeg. Using a rubber spatula, fold in the cheese and about ¾ of the spinach. 
Pour the filling into the partially baked crust placed on a large baking sheet. Sprinkle the remaining spinach on top of the egg mixture, spreading it evenly on top of the quiche. 
Place the pan in the oven and bake for 45 minutes, or until the center is set and the crust is golden-brown. 
Remove from the oven and cool on a wire rack for at least 30 minutes before serving.