Easter Ricotta Pie

MAKE THE PASTA FROLLA:

1. Add the flour, nonfat dry milk (if using) sugar and salt to the bowl of a food processor. Pulse several times to combine the ingredients. (If using zest instead of lemon or orange extract, add it to the flour mixture and pulse to evenly combine.)
2. In a small bowl, whisk together the water, egg yolk and extracts.
3. Add the cold cubed butter and pulse until the butter resembles small pebbles and is evenly distributed throughout the flour mixture.
4. Add the egg yolk mixture to the flour and pulse quickly, 10-12 times until the dough just starts to clump and it holds together when you press some betweeen your fingers.
5. Collect and pat the dough into a ball and transfer to a piece of plastic wrap. Loosely wrap in plastic and pat the dough into a disc about 1" thick. Refrigerate for at least 30 minutes to an hour to chill.
6. Place the chilled dough onto a piece of parchment paper and rest another large piece of parchment over it. Gently roll the dough out to a 13" or 14" diameter, lifting and replacing the parchment after every 2-3 turns, so it doesn't stick. If the dough becomes too soft to work with, place it back in the refrigerator for 5-10 minutes and continue to roll it out using the parchment paper, method. You can also flip the dough over, roll it with the rolling pin, and carefully peel back the parchment and replace it until you get the right size. This dough is fragile, so work quickly and don't be afraid to chill it a few times to make it easier to roll.
7. Place the oven rack at the bottom of the oven. Preheat the oven to 350°.
8. When the dough is rolled to the right dimension, refrigerate it one last time for about 5 -10 minutes to firm up.
9. Carefully peel the top parchment paper off of the top of the Pasta Frolla and discard. In one swift movement, invert the dough into the springform pan (so the dough is pressed into the pan and the parchment is on top.. Press the bottom and sides of the dough through the parchment so it adheres to the bottom and sides of the spring form pan.
10. Carefully peel back the parchment paper. There may be some spots that are torn or need patching, while other areas of the dough have spilled over the rim. Use a sharp knife to trim away the excess and use those bits to patch any holes or tears in the dough and make it relatively even all the way around the sides of the pan. Transfer the dough to the refrigerator while you make the filling.
11. FOR THE RICOTTA FILLING:
12. In a large bowl, combine the ricotta, flour, sugar, eggs, vanilla exract and lemon zest. Whisk it together until the mixture is very well combined and there are no dry bits of flour. Do not use a electric beater as you don't want to beat air into the ricotta mixture.
13. Add the chocolate chips and citron and stir to combine.

ASSEMBLE THE RICOTTA PIE:

1. Remove the crust from the refrigerator and brush the inside with milk to assist with browning and prevent the crust from becoming soggy.
2. Pour the ricotta mixture into the crust and transfer to the lowest rack setting in the oven. Bake for 1 hour without opening the door. Turn off the oven and let the ricotta pie rest for 30 minutes more inside the oven with the door closed.
3. Remove the Easter pie from the oven and let cool to room temperature to serve. If you're not serving until the next day, cover and refrigerate the pie.