Preheat oven at 400° F. Slice apples. Mix sugar, flour, and cinnamon together. Add the apple slices and mix everything together gently with a spatula in a large mixing bowl. Do a taste test at this point, and add more sugar or spices as needed.
Add the ingredients to the pie shell. Make a mountain in the pie shell when adding the apples. The mountain of apples will deflate when you bake the pie.
Seal the edges and add a few vents to the top of the pie with a knife to ventilate the pie.
Cover the edges of the pie with tin foil to prevent the crust from burning.
Bake at 400° F for about 15 minutes, then turn oven to 350 degrees and bake until apples are tender and top is brown. Keep in mind that baking times are merely guidelines. Since home oven temperatures vary, be sure to check pie 5-10 minutes before the end of the suggested bake time or until top is golden brown.
Always bake on the middle rack to allow maximum circulation of heat. Cool pies for 2 ½ hours before serving. If you prefer a pie slice that spreads less on the plate-allow pie to cool for 3-4 hours or overnight at room temperature.Makes 8 to 10 Source: