In an oven-safe pan, melt the butter and sauté your chopped onions/garlic/shallots for 3-4 mins. Season with salt & pepper.
Add chopped squash and celery (or radish), season some more and cook down for 3-4 mins.
Pour in the wine and let simmer for 2-3 mins.
Add chilli flakes and pour in the heavy cream & yoghurt. Season with salt & pepper.
After simmering for a few minutes, add the shredded meat and stir in the peas. Take off the heat!
Layer your puff pastry on top, score a couple of vents and pop it in the oven at 375F for 1hr-1hr10m. Keep an eye every 20 mins to make sure the pastry isn’t over-cooking — if it’s getting too browned at the 50m mark, cover with some foil and keep cooking.
When cooked to perfection, take it out ‘n let rest for 10mins before diving in.