In a saucepan, slowly whisk 1-cup milk into the cornstarch, taking care not to get lumps. Let this sit about 20 to 30 minutes. Then add the remaining milk and the sugar and slowly heat, stirring until nice and thick and smooth. Stir in the two extracts and allow cooling to room temperature, stirring occasionally to keep a "skin" from forming. (TIP: You can also place a piece of plastic wrap on the very surface of the pudding to avoid skin.) Beat the cornstarch pudding well into the remaining ingredients and pipe the filling into shells.
NOTE: If the ricotta seems too wet, place it in a colander lined with paper towel or coffee filters, to separate out some whey. Overnight is best. For a smoother filling, you can lightly whip the ricotta in a food processor or blender.
SERVING TIPS: You can dip the ends of each filled cannoli into melted chocolate then chopped nuts. Or just place a cherry at each end. Add a few drops of green food coloring to the filling to tint pale green and garnish ends of filled shells with chopped pistachio nuts. Be creative.