Tuna Noodle Casserole

Method

1. boil6 min
   salted, 3 minutes short of the packet, drained
   pasta, deliberately underdone. It will absorb liquid from the sauce for thirty minutes in the oven — noodles cooked to package time here come out swollen and pasty, and this single change is the difference between the dish's reputation and the dish
2. saute8 min
   3 tbsp butter, high, mushrooms in one layer and left to brown
   mushrooms, undisturbed until browned, then + onion + celery until soft. Mushrooms are about ninety percent water and must be given room and heat to drive it off — crowded, they release that water and simmer grey, which puts the moisture into the casserole instead of leaving it in the pan
3. whisk6 min
   flour into the vegetables, then warm milk a splash at a time
   + flour, cooked one minute, then + warm milk gradually, whisking smooth between additions until the sauce coats a spoon. Warm milk keeps the roux from seizing into lumps; the flour has to cook a minute first or the sauce tastes pasty however long it bakes
4. fold5 min
   off the heat, cheese in first, then everything else
   + cheddar + salt (+ soy sauce, + pepper, + lemon juice), stirred until melted, then + noodles + tuna + peas (+ parsley). Cheese off the heat so it emulsifies rather than splitting. Flake the tuna in large pieces and fold gently — stirred hard, it disintegrates into the sauce and the dish loses the only texture it has besides the crust
5. bake25 min
   190°C, buttered dish, buttered crumbs on top, uncovered
   until bubbling at the edges and the top is deep golden. Uncovered throughout: a lid traps steam and the topping goes soft, and the browning is Maillard chemistry on the buttered crumbs that needs a dry surface above about 150°C
6. rest5 min
   on a rack, out of the oven
   before serving, so the starch-thickened sauce sets enough to hold a spoonful together. Straight from the oven it runs across the plate; ten minutes and it will have gone stodgy, so five is the window