Add flour, granulated sugar, cocoa powder, cinnamon, nutmeg and salt to a food processor and pulse until blended. Pour in melted butter and pulse until well combined then add egg white and pulse until blended.
In a bowl combine juice and vinegar, with processor running slowly pour in juice mixture and pulse just until mixture begins to come together.
Divide dough into two pieces, shape into balls and transfer to a resealable bag. Chill in refrigerator 30 minutes - 1 hour. Preheat oven to 400 degrees during last 10 minutes of refrigeration.
Meanwhile prepare filling. In a mixing bowl, using a rubber or silicone spatula, blend together Ricotta and Mascarpone cheese while running and pressing mixture along bottom of bowl to remove any lumps. Fold in powdered sugar. Cover and chill 30 minutes (or until ready to use).
Roll each chilled dough out on a lightly floured surface (dust top with flour too) into a 14-inch circle, to about an 1/8-inch thickeness. Cut into circles using a 2 1/2-inch round biscuit cutter.
Transfer rounds to an ungreased mini muffin tin, pressing evenly into sides and bottom of muffin well. Spray tops evenly with vegetable oil spray (I just poured vegetable oil in to my Misto to spray).
Bake in preheated oven 11 - 13 minutes until lightly golden (I liked these best crisp). Remove from oven and transfer to a wire cooling rack to cool completely. Once cool dip tops in chocolate if desired then into coating if using (such as pistachios) and allow chocolate to set.
Remove cannoli filling from refrigerator, transfer to a piping bag fitted with a tip (or you can use a large resealable bag and cut the tip of the end). Pipe filling into cups and sprinkle with chocolate chips and dust with powdered sugar. For best results serve within 2 hours. Store in refrigerator.
*Update - some have mentioned their dough being too thick and not elastic enough to keep a shape when rolling and cutting, so I'v updated it to be 6 - 8 Tbsp of juice rather than just 6 Tbsp.
**You can add 2 Tbsp more if you'd like it a little sweeter.