Preheat your oven to 425°F (220°C).
Prepare the apple filling by mixing the sliced apples with lemon juice, cinnamon, nutmeg, sugar, and flour in a large bowl.
Roll out the pie crust and fit it into a tart pan, trimming any excess.
Pour the apple mixture into the prepared crust, arranging the slices evenly for an appealing presentation.
Brush the crust with the egg wash to give it a beautiful shine.
Bake the tart in the preheated oven for 25-30 minutes, or until the crust is golden brown and the apples are tender.
Let the tart cool for at least 15 minutes before serving.
Serve warm or at room temperature, optionally with whipped cream or vanilla ice cream.