In a medium size, non-reactive sauce-pot, place berries and maple syrup over medium heat. Bring to a boil, immediately reduce to a simmer and cook stirring occasionally and until berries begin to release their juices and thicken slightly, about ten minutes. Turn off heat, add lemon juice, let cool to room temperature.
Line a 9 x 5 inch loaf pan with plastic wrap, letting 3″ hang over on all sides. Press plastic wrap into pan, leaving no air space.
Trim bread slices to fit pan, place a single layer in pan bottom. Using a slotted spoon, place generous single layer of fruit over first layer of bread.
Dip second layer of bread slices into pot with berries for half a minute per side to soak up excess fruit juices. Place over berry layer. Repeat with two more layers of fruit and bread. Finish with a layer of bread, top with remaining juices. Fill to just above rim of pan.
Fold over excess plastic wrap and over loosely with additional plastic wrap as needed. Place loaf pan on a rimmed cookie sheet to catch any overflowing juices. Cover with a second cookie sheet and place several heavy cans on top to press and weigh down pudding. This allows berries to release all their juices into the bread and forces pudding to hold it’s shape nicely. Refrigerate 8 hours or overnight.
To unmold, remove top layer of plastic wrap, invert onto serving platter. Lift off loaf pan and peel off plastic wrap lining.
Serve one slice per person. Optional: Garnish with a dollop of real whipped cream and a sprig of fresh mint. Drizzle a teaspoon or so of pure maple syrup over the whipped cream. Serve immediately.