In a mixer fitted with a paddle attachment (or using a hand mixer), cream the butter until smooth. Add the confectioners' sugar and mix. Add the eggs and mix. Add the flour and mix until almost incorporated. Add the hazelnuts and mix just until smooth, being careful not to over mix the dough.
Form the dough into 2 disks and wrap in plastic wrap. Chill at least 2 hours or overnight. If the dough is refrigerated overnight, remove it from the refrigerator 30 minutes before using. Roll out both disks, cut them out a little bigger than the size of your individual baking dishes, and chill while you make the filling.
Preheat the oven to 375 degrees F. Drain the cherry juices into a medium saucepan; you should have about a cup of juice. Add the cornstarch, sugar, ginger, if using, and lemon juice, and bring to a simmer over medium heat, stirring to dissolve the cornstarch. When thickened, turn off the heat, stir in the cherries, and set aside to cool slightly.
Divide the cherry filling among the baking dishes. Carefully place the rolled-out crusts on top. To decorate them, brush the surface of the crust with milk, sprinkle lightly with sugar and use a sharp small knife to make a cross hatching pattern, cutting one vent hole in the center. You may also cut out strips from the leftover dough, and make designs or cherries from it, and adhere them to the top with a little water. Then wash with milk and sprinkle with sugar.
Place the pies on a sheet pan to catch any juices that boil over. Bake until the crust is golden brown and the juices are bubbling at the vents, 25 to 30 minutes. Let cool to room temperature. Serve at room temperature.