The -sz- spelling gives it a Polish appearance but the -enko ending says 'Ukrainian'. There is a Ukrainian surname Miloshenko, as well as Milashenko. I would venture to suggest that they are the same, though without any evidence to back this up. Milosh is probably the Slavic male given name meaning something like "kind, generous, charitable". So Miloshenko probably means "descendant of Milosh" and perhaps Milaszenko means the same.