Can War Magic from Eldritch Knight be used to cast Booming Blade twice with Action Surge?

I've been tinkering with an EK using PAM, Pike with push mastery and Speedy. Basic play would be to Booming Blade, push the melee mob away and then step back 5 feet so it would likely need to move (triggering the BB secondary damage) and potentially move into my threatened area for the Reactive Strike reaction. Speedy is for the extra 10ft of movement because it would be very much movement based play and then for giving mobs disadvantage on opportunity attacks against me if required (e.g. multiple mobs, etc). There's Extra Attack and the bonus action from PAM in there too but I don't think those are relevant to my question.

Here are the relevant rules:

War Magic:

When you take the Attack action on your turn, you can replace one of the attacks with a casting of one of your Wizard cantrips that has a casting time of an action.

Action Surge:

You can push yourself beyond your normal limits for a moment. On your turn, you can take one additional action, except the Magic action.

Once you use this feature, you can’t do so again until you finish a Short or Long Rest. Starting at level 17, you can use it twice before a rest but only once on a turn.

Casting Time - One Spell with a Spell Slot per Turn:

On a turn, you can expend only one spell slot to cast a spell. This rule means you can’t, for example, cast a spell with a spell slot using the Magic action and another one using a Bonus Action on the same turn.

Booming Blade:

Casting Time: 1 action

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects and then becomes sheathed in booming energy until the start of your next turn. If the target willingly moves 5 feet or more before then, the target takes 1d8 thunder damage, and the spell ends.

My reading is that if I Action Surged I could cast Booming Blade a second time using the EK ability because it's not the Magic Action and it's not using a spell slot. The movement damage wouldn't stack on the same creature because "the effects of the same spell cast multiple times don’t combine", so I'd need to split damage across mobs.

Is this correct?