The day before you plan to serve the pudding, butter 8 (1-cup) ramekins and line them with plastic wrap. Cut the crusts off the bread and, using a round cutter the size of the interior of the bottom of the ramekin, cut out 16 bread disks. Lay 8 of them in the bottoms of the ramekins. Cut the rest of the bread in strips and line the walls of the ramekins. Reserve the remaining 8 disks.
Sprinkle the gelatin over the cold water and let it soak to sponge for 5 minutes. In a saucepan, carefully combine the apple juice concentrate and all the berries. Bring the mixture to a boil and cook until the strawberries begin to soften, about 1 minute. Immediately turn off the heat. Add the sponged gelatin to the berries mixture and stir to combine.
Divide evenly by spooning the berries and their juice into the bread-lined ramekins. Cover with remaining bread disks. Place the ramekins on a sheet pan and cover them with plastic wrap. Place a second sheet pan on top of them and place a weight on it, like a 1/2 gallon juice can and chill overnight. The bread should become completely soaked with berry juice by the next day. These will keep for 2 days at this point.
When ready to serve, whip the cream with an electric mixer at high speed until it forms soft peaks. Remove the puddings from the refrigerator and remove the plastic wrap on top. Carefully turn the pudding out onto dessert plates tugging on the plastic wrap lining if needed. Serve with whipped cream on top.