Preheat oven to 400 degrees F.
On a baking sheet arrange bread slices in one layer and toast in middle of oven, turning them if necessary, until golden brown on both sides. Transfer bread to a rack to cool.
In an 8-inch square glass baking dish set inside a larger shallow baking dish arrange half of bread slices, overlapping slightly if necessary and trimming to fit, and top with half of unchilled fruit mixture. Layer remaining bread slices and unchilled fruit mixture in same manner. Cover surface of pudding with plastic wrap. Put another 8-inch square glass or metal baking dish on top of plastic wrap and weight pudding evenly with about 6 pounds of weight (such as cans of food). Chill pudding at least 8 hours and up to 1 day.
Just before serving, remove weights, baking dish, and plastic wrap from pudding, reserving juice that has spilled over into larger baking dish, and cut pudding into 6 portions. Transfer 4 portions with a spatula to plates and spoon reserved juices and chilled fruit mixture around them. Serve pudding with Sour Cream Mascarpone.
Recipe courtesy of Gourmet Magazine