Place the berries, water, sugar and vanilla in a saucepan over medium heat. Bring to a simmer. Cook for 5 minutes and remove from heat. Let cool.
Line a bowl with plastic wrap on all sides, overlapping the edges by a good 4 inches. Spray the plastic with cooking spray. Cut the bread slices to fit all around the bottom and sides of the bowl with some slices to spare for the top.
Fold the whipped cream into the cooled berry mixture and fill the center of the bread lined bowl. Place the remaining bread slices to cover the top of the pudding and pull the extra edges of the plastic wrap over the top.
Place a small plate on top and weigh down with a can of something or other. Refrigerate at least 3 hours or overnight.
Unmold by removing can, plate and unfolding the top of the plastic wrap. Place a serving plate over the top. Flip it over and remove the bowl and remaining plastic wrap. Slice into big wedges and garnish as desired.