Buttermilk Potato & Leek Pie

Directions

1. Preheat oven to 350°. Line two large baking sheets with parchment paper and set aside. Keep pie shells in the refrigerator until ready to use.
   
   Rinse and peel potatoes. Place one in a bowl, covered with cold water and cut the remaining two potatoes into large chunks. Place the diced potato in a small saucepan and cover with cold water and a lid. Bring to a boil over high heat, then lower to medium heat and simmer for about 15 minutes until fork tender.

2. Grate the remaining potato and keep in cold water. Peel and grate the apple and place in a small bowl, covered with plastic wrap to prevent it from browning.
   
   Dice onion and set aside. Using only the white part of the leek, cut off the bottom root end, slice in half lengthwise, and then dice into half-moon pieces.  Place leeks into a colander and rinse off any dirt.  Allow to drain. Finely mince the two cloves of garlic.
   

3. In a large, non-stick skillet, over medium heat, melt 3 tablespoons of butter. Once melted, add the onion and the leek.  Sauté for 5 minutes. Drain the grated potato, squeezing out any excess moisture, and add to the onion and leek mixture, along with the grated apple, 1 teaspoon salt, ¼ teaspoon black pepper and 1/8 teaspoon ground nutmeg. Sauté for another 6-8 minutes, just until everything has softened, then turn off heat and allow to cool.
   
   Once boiled potatoes are done, drain and add the remaining 5 tablespoons of unsalted butter, ¼ cup of buttermilk, 1 teaspoon of salt and mash until fluffy.
   

4. In a large bowl, whisk the eggs, remaining ¾ cup of buttermilk, 1/2 teaspoon salt, and ¼ teaspoon black pepper.
   
   To assemble, place one pie shell on each baking sheet. Divide the mashed potato mixture amongst the two pies and spread out evenly on the bottom. Next, top with a layer of 1 cup of shredded cheese. Then, divide the grated potato and leek mixture amongst the two pies. Poke several holes into each pie to allow for the egg and buttermilk mixture to sink into the pies. Divide liquid mixture so that approximately ¾ cup goes into each pie. Slowly pour on top, from the center out towards the edges. Top each pie with the remaining shredded cheese.
   
   Bake pies on the bottom rack of the oven for 30 minutes, making sure both are level to avoid having the filling from spilling over. After 30 minutes, rotate the pans and bake for another 20 minutes until just golden. Allow to cool for 5-10 minutes before slicing and serving.