@JeremyECrawford Does the extra attack feature of Bladesong Wizard allow you to cast Green Flame Blade and also make the second attack?
— Some sort of cat (@Goldleej) November 12, 2015
Extra Attack requires the Attack action. Casting a spell (cantrips included) requires the Cast a Spell action. #DnD https://t.co/gxlZIGTx9W
— Jeremy Crawford (@JeremyECrawford) November 12, 2015
Can a monk/sorcerer use Green flame blade with unarmed attack?
“As part of the action used to cast this spell, you must make a melee attack *with a weapon* against one creature within the spell’s range…” *= emphasis mine. The spell literally tells you whether or not you can us an unarmed attack with GFB. (You can’t — it must be with a weapon. The distinction here is that the spell specifically cites needing to use a weapon attack vs the more broad melee attack.)