Whisk dry ingredients (flour, sugar, and salt) together.
Cut in cold butter until crumbly.
Stir in sourdough starter/discard and egg until a shaggy dough forms; knead briefly until smooth.
Shape into a disc, cover, and rest 30 minutes (or 4–12 hours for long fermentation).
Heat neutral oil to 350°F and strain ricotta.
Roll dough thin and cut into rounds.
Wrap dough around greased cannoli forms and seal edges with egg wash.
Fry 4–5 at a time for about 2 minutes, turning once.
Drain on paper towels and remove forms when cool.
In a separate bowl, whisk filling ingredients until smooth; fold in add-ins.
Fill shells, dust with powdered sugar, and serve.