I think you may be onto a winner in going down the (proper) croissant line. With a real croissant (not a puff pastry one), you work with the dough cold and let it prove for a long time, so this enables you to work it as you would a puff pastry - meaning, slow prove the dough at a cold temperature and then use the yeasted dough to form a puff pastry before shaping and second proving.
I may experiment with this myself tomorrow, it looks interesting. This is what I would do:
150g Very Strong White Flour
100g Plain (White) Flour
10 - 15g yeast depending on how old it is etc.
160g Cold Water
6g Salt (depending on how strong your salt is)
Also get a bread stone - I got a terracotta tile (it MUST be unglazed - the glazes contain lead) from a diy store for about £5 and it works brilliantly.
Add 3/4 of the yeast, strong flour, water and salt into a bowl. Stir lightly together and set aside to rise. Allow it to rise until it has overproved - risen and then collapsed.
Add the remaining flour and yeast, knead together and leave to rest covered in in your fridge or somewhere cool.
When doubled in size, knock back and roll out as you would to make puff pastry (a cross shape with a slightly thicker bit in the middle). Bash the butter between layers of greaseproof paper to loosen it and reshape into a square.
Put the butter in the middle and fold the cross around it - use opposites. Roll into a rectangle. Fold the bottom third up to the middle and then the top third over the top of it. Do a quarter turn and roll out another rectangle. Refrigerate and repeat the rolling process 1 - 2 times. (If this stage makes little sense then there are lots of puff-pastry tutorials on the web or in books, you should find it easy to see what I mean). I wouldn't roll it more than 4 times, maybe even just stick at 3. You don't want full puff pastry, just layers of fat.
Put your oven to preheat at your highest temperature - around 230 degrees C with your bread stone in it.
Roll or stretch your pastry into shape inside your tray/dish and leave to prove for half an hour to an hour in a moderately warm place, NOT the obligatory airing cupboard! 20 degrees C will do fine. DO NOT ADD THE TOPPINGS.
After the second prove your oven should be well up to temperature so put the whole thing in for a few minutes, monitoring carefully. When the crust starts to form in the middle then you can take it out, add your sauce and toppings before returning to the oven to complete cooking.
I'm not saying this will work, but it might be a good place to start your experimentation.
Another thing I've noticed while typing this recipe and thinking, observing etc. is that the dough is very light coloured, with a texture that looks quite similar you French baguettes. My understanding is that the yellowy brown colour of dough comes from incorporating air during the kneading process - the way to avoid this seems to be high hydration dough with a long proof time, allowing the glutens to align without the process of kneading them into shape. What I'm saying in a roundabout way is that a high hydration dough, long proving and little handling may produce that stretchy layered look too, so if your first experiment is nowhere near the mark then that might be the next line of inquiry to pursue.
Hope this helps.