How do I best cut florentines from a finished (baked) baking tray?

I have baked a tray of florentine pastry, and I have spread chocolate on it (dark and milk). It’s about 35 x 35 cm. Now I’d like to make cookies out of it.

I know recipes say to cut the pastry when it’s still warm, but it was just far too thin and fluid to do so: it would basically have amounted to pushing a knife into almond flakes which are floating in a sauce; it didn’t seem realistic at all.

The pastry is nice and crisp and thin now (as thin as I could get it, maybe 3–5 mm), as it should be. The consistency is a bit like semi-hard caramel. but of course with almond flakes over the entire surface (so much less hard, easier to break/cut). How can I best cut (square-shaped) cookies out of it?

I don’t think breaking is an option, so it has to be cutting or sawing? I see no option but to use a large kitchen knife. Should I press it down until it snaps? Or should I move it along the length of the desired cut (‘sawing’)? Should I use a smooth knife or a serrated knife (probably not)? Or is there anything else you can recommend?

I’m afraid I might break the pastry into irregular shards and bits if I do it wrong, but I haven’t tried yet without asking you!

P.S. It doesn’t stick to the baking-paper much, so that won’t be an issue.

P.P.S. You see the orange in the picture which I grated for the zest.

Epilogue: I ended up cutting them with a non-serrated knife, which I put in a pan of very hot water between ‘cuttings’, to partly melt the cut (wipe with paper towels in between). I cut by moving the knife up and down the length of the cut (‘sawing’), but I did also exert some downward pressure. It worked well enough, except for some breaking at the edges which were not flat at the bottom (because of the uneven baking tray).