In a mixer, whip the mousse and milk on high speed until the mouse is thickened. Finely chop 4 of the strawberries, and add them to the mousse. Blend for 1 more minute and refrigerate for a least an hour.
Spoon mousse mixture into a piping bag. Pipe the cannoli shells full of the mousse. Make a design on the serving plate with the chocolate syrup. Slice the remaining strawberries, and place around the plate with the blackberries.