Unfortunately not much you can do to keep them as cake...... BUT you could toss them into a food processor and blitz them and then add enough chocolate ganache to moisten them and make cake pops!
Cut into pieces. Dip them in any Sweet syrup ( coffee syrup, sugar syrup, any fruit juice). Layer them in a glass or bowl. Top with ur choice of ice cream and dry fruits or fresh fruits. Refrigerate for some time. Serve as a dessert.
To prevent the hardening of cake put in the fridge with a few slices of bread. The bread becomes hard but cake stays nice and moist