Butter a 3-quart baking dish; place bread evenly in dish and set aside. In a small bowl combine peanut butter, half of the cream cheese, and the 2 teaspoons sugar. Use 2 spoons to drop mounds of peanut butter mixture into crevices among the bread cubes. Drop mounds of jam into empty crevices. Cube remaining cream cheese and place in any empty spaces.
In a large mixing bowl whisk the eggs well until blended. Whisk in the milk, cream, 6 tablespoons sugar, vanilla, salt, and nutmeg. Pour egg mixture over bread in dish. Cover and chill at least 2 hours or overnight.
Remove baking dish from refrigerator and let stand at room temperature for 30 minutes. Preheat oven to 350 degrees F. Uncover dish. Drizzle with butter and sprinkle on crushed sugar cubes. Bake for 45 to 50 minutes or until center is puffed and golden. Remove from oven. Cool on a wire rack for 10 minutes before serving. Sprinkle with blackberries.