Prepare Shortcrust Pastry: In a stand mixer or by hand, combine sugar, cubed cold butter, a pinch of salt, and flavor enhancer. Knead while adding egg yolks and lemon zest until absorbed. Gradually add 00 flour and knead until classic shortcrust consistency is achieved. Form a loaf, wrap in cling film, and refrigerate for at least 3 hours.
Prepare Filling: Drain sheep ricotta to remove liquids, then pass through a sieve to remove lumps. Mix ricotta with sugar and grated orange zest. Add dark chocolate chips and mix well. Refrigerate until ready to use.
Roll Out Pastry and Line Molds: Remove shortcrust pastry from fridge and soften slightly. Flour work surface and roll out a little more than half the dough to 4 mm thickness. Cut disks to fit greased aluminum molds and line molds with pastry.
Add Biscuit Crumbs: Crumble dry biscuits roughly by hand and sprinkle a small amount on the bottom of each lined mold to absorb moisture from filling.
Fill Molds: Transfer filling into a piping bag and fill molds almost to the edge. Sprinkle more crumbled biscuits over the filling surface.
Seal with Pastry Discs: Roll out remaining pastry to 4 mm thickness and cut disks matching mold size. Moisten edges of molds with water, place pastry discs on top, and press edges lightly to seal.
Bake: Place molds on a baking tray and bake in a preheated static oven at 175°C (347°F) for about 35-40 minutes.
Cool and Decorate: Unmold the mini cassatas once cooled. Dust with icing sugar using a grid as a stencil for decoration.