In a large bowl, flake the cake into crumbs with a fork.
Stir in the mascarpone and cherries until completely blended.
Place in refrigerator for a minimum of 4 hours and up to 2 days to make the mixture easier to roll into balls.
Roll mixture into 1-inch balls, place on cookie sheet and place in freezer for 20-30 minutes to stiffen balls.
Melt white chocolate over double boiler.
Dip balls into chocolate, one at a time and covering all sides, before placing on parchment or wax paper to set (I do this by dropping them into the chocolate and using two forks to coat them and than retrieve them. Make show to lightly tap the fork to the edge of the double boiler top to get rid of excess).
Let set and serve.
These last for a good amount of time in the refrigerator, about 1 week.