Chicken Pot Pie

Method

1. mix6 min
   cold, by hand
   flour + 0.75 tsp salt + cold cubed butter, pressed into flat flakes rather than crumbs, then + ice water just until it holds when squeezed — visible sheets of butter are what steam the pastry into layers, so stop while the dough still looks underhydrated
2. rest30 min
   refrigerated, wrapped
   dough — the flour finishes absorbing the water and the gluten slackens, so the round rolls out without springing back or tearing
3. poach12 min
   bare simmer, lid ajar
   chicken stock + bay leaf + chicken, until the pieces are just firm, then lift out the meat and keep the liquid — a real simmer would tighten the thigh meat and squeeze it dry before it ever reaches the oven, and the stock is now the sauce
4. sweat8 min
   medium, no browning
   3 tbsp butter + onion + carrot + celery + a pinch of salt, covered, until the onion is translucent and the carrot bends — root vegetables will not soften further once the sauce thickens around them, so this is the only chance to cook them through
5. mix3 min
   medium, constant stirring
   + flour, cooked until it smells like toast but stays blond, which cooks off the raw-paste flavor while keeping the starch's full thickening power
6. simmer7 min
   medium-low, whisking
   + poaching liquid a ladle at a time, then + milk + thyme + black pepper + remaining salt, until it coats a spoon and holds a line — a loose sauce will boil up through the vents and a stiff one turns to glue in the oven, so aim slightly thicker than gravy
7. fold2 min
   off heat
   + poached chicken + frozen peas, then spread into a shallow 8-inch dish and let it cool to warm — filling straight off the stove melts the butter out of the raw pastry on contact and the crust bakes flat and greasy instead of layered
8. top5 min
   filling + rolled dough draped over and pressed to the rim, egg-washed; the seal at the edge is what holds the lid up as the filling boils underneath
9. score1 min
   crust, three cuts through to the filling — steam has to leave somewhere or it lifts the pastry off the sauce and leaves a raw underside
10. bake40 min
    400°F / 205°C, tray beneath
    pie, until the crust is deep brown and the sauce bubbles visibly at the vents; pale crust means the interior starch is still slack
11. rest10 min
    out of the oven
    pie — the sauce is thinner than it looks at 200°F and will run off the spoon; ten minutes lets the roux set so a cut portion stands up