For crust: Combine flour, sugar, and salt. Combine with orange zest and shortening. Add egg yolks one at a time. Work with hands until dough is manageable. Add milk only to desired consistency. Form into ball, and cover for 30 minutes. Press dough into bottom(& very slightly up sides) of deep 10" springform pan.
Preheat oven to 350 degrees.
For filling: Beat ricotta and sugar, then add eggs 1 at a time mixing until incorporated. Add orange juice(or vanilla), and reserved maraschino cherry juice. Mix until well blended. Fold in by hand the cherries and grated chocolate.
Pour filling in crust. Optional: grate some extra chocolate on top. Bake at 350 degrees for 1 hour until top lightly browned. Turn off oven and cool in oven with door open. Serve chilled or room temp.