Peach crumble slab pie

Score a large shallow X through the skin of each peach, around the fruit one direction and 90 degrees the other, cutting barely through the skin and not into the flesh.

Drop the peaches into rapidly boiling water six at a time for 10 to 15 seconds, until the skin starts to pull away from the score marks, then move them to an ice bath.

Peel the peaches, using a paring knife on stubborn spots, then cut down the natural line, separate the halves, pull out the pit and cut into bite-sized pieces.

Add the demerara sugar, a little kosher salt, the ground ginger, cinnamon and nutmeg, three tablespoons of lemon juice and two teaspoons of vanilla to the fruit, holding back the cornstarch. Toss and leave to macerate.

For the crumble, combine two cups of old fashioned rolled oats, two cups of all-purpose flour, demerara sugar, salt and a couple of teaspoons of ground cinnamon.

Smash in the cubed butter until it disappears with no discrete pieces and no floury bits, and the mixture holds together in big crumbs; a stand mixer with the paddle on low does the same job.

Chill the crumble.

Beat the cold dough with the rolling pin, working crosswise and lengthwise and turning it 90 degrees, to soften the butter without warming it; let it sit a couple of minutes if it cracks.

Roll the dough out to about an inch and a half beyond the bottom of the pan all the way around, squaring off the edges and keeping it unstuck from the surface so it does not stretch.

Roll the dough onto the rolling pin, unroll it over the pan and let it slump into the corners under its own weight without pressing it in; trim the excess with a knife.

Chill the lined pan so the dough relaxes and the butter stays cold.

Preheat the oven to 425 -- starting hot sets the crust and browns the unbaked bottom.

Ladle a couple of tablespoons of the macerating liquid onto the cornstarch and mix smooth with a fork to make a slurry.

Pour the rest of the liquid into the skillet, leaving the fruit behind, and rapidly boil it down to a syrup.

Off the heat, stir in the cornstarch slurry, bring back to a boil for 10 seconds to activate the starch, and it thickens.

Cool the reduction quickly by setting the skillet on ice, then scrape it back into the fruit and mix.

Spread the filling over the chilled crust in a single layer of fruit.

Cover it completely with a generous layer of the chilled crumble, out to the edges and corners.

Bake at 425 for 20 minutes, then turn the oven down to 350 and bake another 40 to 45, 45 minutes to an hour in total, until the crust is golden brown at the edges, the filling is bubbling and the crumble is brown.

Put foil under the sheet tray, which catches butter drips from around the edge.

Cool completely so the filling sets, then cut into squares.