Zest lemons with a zester to get 1 teaspoon zest. Juice the lemon using a citrus juicer to get 2 tablespoons lemon juice. Set aside.
You can buy pie crusts, or make them homemade. Be sure to chill pie crusts (tightly wrapped in plastic wrap) for at least 30 minutes before rolling them out. It’s best to keep everything as cold as possible! Chill pie dough, apple pie filling, and pie before baking.
Peel and core apples. Dice into 1/2-inch cubes, measure 7 cups, and set aside.
In a large pot over medium heat, melt butter. Add diced apples, lemon juice, and zest. Stir in brown sugar, cinnamon, allspice, cloves, nutmeg, and salt. Cook, stirring occasionally, for 6–8 minutes until juices thicken and apples begin to soften.
In a small bowl, mix granulated sugar and flour. Sprinkle over the apple filling on the stovetop and stir. Cook for 4–5 minutes, stirring often until the filling thickens. Remove from heat and let sit for 5 minutes. Stir in vanilla and Greek yogurt. Refrigerate the apple filling until chilled, about 45 minutes.
In a small bowl, whisk together the egg and milk with a fork until smooth. Set aside.
Place a pie crust in the bottom of a 9.5-inch pie pan. Lightly brush with egg wash. Spread cooled apple filling evenly over the crust. Cover the top with pie crust (see note 3). Press all around edges to seal the two crusts together. Trim or tuck excess crust so it is flush with rim of the pan. If desired, crimp edges (see note 4). Place assembled pie in fridge and chill for 30 minutes to an hour. Preheat oven to 400°F.
Take out the pie and brush all but the crimped edges with egg wash. Sprinkle optional sparkling sugar (see note 2) evenly over the pie. Set the pie on a sheet pan lined with parchment paper and bake for 55–65 minutes, or until the crust is a deep golden brown. If crust is browning too quickly, use a pie shield (see note 5).
Cool completely, at room temperature, before cutting into pie and serving. If the pie is cut straight out of the oven it’ll be runny and wet; it needs time for the filling to become juicy and thick. I typically wait 3–5 hours before cutting into the pie. If desired, serve with fresh whipped cream or vanilla bean ice cream.
