How best to add a layer of mini marshmallows to this traybake recipe?

Hi all,

I’ve been trying to make a special treat for my partner based on the classic millionaire’s shortbread (shortbread base, caramel layer, chocolate layer). He’s suggested it would be nice if it also had a marshmallow layer incorporated. I have both Fluff and mini marshmallows on hand, my partner prefers mini marshmallows. So I am hoping to incorporate them somehow when I make this recipe next week:

https://topwithcinnamon.com/millionaires-shortbread/

What would be the best way to do it? Place them on top of the caramel layer before chilling in the fridge? I don’t mind if the top is lumpy/textured.

Thank you