Using a wooden skewer or the end of a wooden spoon handle, poke holes generously throughout the entire cake.
Add the pudding mix and milk to a large bowl and beat with a wire whisk until smooth.
Pour the pudding over the top of the cake, filling in all the holes. Place the cake in the refrigerator while you prepare the ganache.
Add the heavy cream to a small saucepan and place it on the stovetop over medium heat. Stir the cream frequently until it is very hot, but not boiling.
Add the chocolate chips to a large heat-safe bowl and pour the hot cream over the top. Stir until all the chocolate is fully melted and the mixture is fully combined and smooth.
Allow the ganache to sit at room temperature for about an hour, or until it has cooled completely.
Beat the cooled ganache with an electric mixer until fluffy - about 2-3 minutes.
Remove the cake from the refrigerator and spread the whipped ganache evenly over the top.
Top the cake with the desired amount of Maraschino cherries.