It’s New York. It’s Summer.
Blueberries are $5/kg.
Blackberries taste like blackberries.
This pie was inevitable.

A New York Times recipe, with blackberries for a bit of bite,
and lattice because that’s the whole point of pie.
You’ll need to start the dough a few hours ahead
so it has time to chill/rest, and the fruit will also need
to sit around for an hour getting juicy before it’s ready to bake.

Gather:
For the crust
220 g butter (2 sticks) — cold
290 g plain flour (or whole wheat)
35 g cornmeal¹
35 g sugar (caster or raw)
1/2 tsp salt
1/2 cup iced water

For the filling
5 cups blueberries
1 cup blackberries
1 lemon — zest and juice
135 g sugar (caster or raw)
30 g cornflour
1/4 tsp xanthan gum²

Before baking
2 tbsp milk
2 tbsp demerara sugar

To serve
Vanilla ice-cream (non-negotiable)

Then:

1. Several hours before you’re ready to bake, prep the crust:
   Cut the butter into small cubes, and chuck it into a large mixing bowl with the flour, cornmeal, sugar and salt.
2. Using your fingers or a pastry cutter, rub/blend the butter into the dry ingredients until it’s the consistency of clumpy, damp sand.
3. Add 2 tbsp of the iced water, and mix it in using your hands. You just want the dough to form a cohesive ball but it doesn’t need to be smooth or kneadable. If necessary, keep mixing and adding water, half a tablespoon at a time, until you get there.
4. Split the dough into two halves (I like to weigh each one to make sure they’re even), smoosh them into discs, wrap individually in plastic, and pop them in the fridge for a few hours.
   …
5. About an hour before you’re ready to bake, prep the fruit:
   Measure out 2 cups of the blueberries and set them aside for later.
6. Put 3 cups of the blueberries and all of the blackberries in a very large mixing bowl (or container).
7. Add the lemon zest, lemon juice, cornflour and xanthan gum, and stir gently until all the berries are evenly coated. Set this aside for about an hour, til it’s nice and juicy.
   …
8. An hour later:
   Take the dough out of the fridge so it’ll be ready to work with in 5 minutes.
9. Turn on the oven to 205°C/400°F.
10. Add the remaining blueberries to the fruit mix, and stir again — gently.
11. Go back to the dough. If it’s too firm to work with, hold the first disc in your hands for a couple of minutes — you want it to be workable but not soft.
12. Roll out the first disc of dough until it’s an inch or so larger than your pie dish, lay it in the pie dish, do whatever edging you prefer³, then dump the berries in there.
    
13. Do a lattice, if you dare.⁴
14. Brush the top with milk, then sprinkle with demerara sugar.
    (Having a kitchen in New York is a miracle, so I can live with the broken light.)
15. Put the full pie dish on a baking tray/sheet and bake for 25 minutes, then bring the temperature down to 175°C/350°F and bake for another 35 minutes, or until the crust is golden all over and the juices have gone jammy.
16. Remove the pie from the oven and allow it to cool on a rack, almost to room temperature. Serve ever so slightly still-warm, with good old-fashioned, not-too-rich, bought-it-from-the-supermarket vanilla ice-cream.
    

Notes:
¹You could also use a regular all-butter crust recipe, but the cornmeal gives this one a bit of crunch to set off the smooshy berries inside.
²After countless unset pies — hot fruit swimming in a pool of unthickened juice — I’ve decided that cheating is the solution. A little xanthan gum goes a long way.
³Yes, that’s a link to Martha Stewart. Kill me now.
⁴To make up for Martha, this is one of the Four and Twenty Blackbirds sisters teaching you how to make their all-butter crust from beginning to end. Their crust is the gold standard, just ignore me and listen to Melissa.