Preheat oven to 375°F.
In a bowl, combine flour, sugar, and salt.
Cut in butter until mixture resembles coarse crumbs.
Add ice water gradually until dough forms.
Shape dough into a disk and roll out on a floured surface.
Transfer dough to a baking sheet.
In a small bowl, mix hazelnut spread or ground hazelnuts, butter, sugar, flour, and egg yolk until smooth.
Spread a thin layer of the hazelnut mixture over the center of the dough, leaving a border.
In another bowl, combine apples, sugar, cinnamon, nutmeg, lemon juice, and flour.
Place apple mixture over the hazelnut layer.
Fold edges of dough over the filling, leaving the center exposed.
Bake 30 minutes until crust is golden and filling is tender.
Let cool slightly before serving.
Serve warm with vanilla ice cream.