Preheat your oven to 375°F (190°C).
Prepare the filling by mixing the sliced apples, sugar, cinnamon, nutmeg, and lemon juice in a bowl.
Cut the pie crust into circles that fit the top of your mason jars.
Layer the apple filling into each mason jar, filling them about two-thirds full.
Place the cut pie crust on top of each jar and crimp the edges with your fingers.
Brush the tops with beaten egg for a golden finish.
Bake in the preheated oven for 25-30 minutes or until the crust is golden brown.
Let them cool for at least 10 minutes before serving.