Preheat oven with a baking sheet on the middle rack to 425 degrees. Prepare pie crust and line a pie plate with a single layer of pie dough.
Zest lemon into sugar and rub between your fingers until combined, set 2 T. aside. Add cornstarch and apples to citrus sugar and toss to combine. Scoop the apples into the bottom crust, leaving any amassed juices in the bottom of the bowl.
Roll out second crust. Cut the top dough into inch wide and half-inch wide ribbons. Place down one 1” and ½” strip of dough, leave some space and then repeat so you have 3 sets of pairs each horizontally and vertically. Folding dough strips back and forward again to create a plaid basket weave. Trim 1 inch around the pie and tuck the ends to finish the pie. Crimp crusts together, brush with milk to make the top shiny, and sprinkle the reserved sugar and cinnamon for sparkle and crunch.
Bake at 425 degrees for 20 minutes, and then lower oven temperature to 375 degrees and bake for 30 minutes more or until the pie juices are bubbling. Cool and allow juices to thicken before serving.