The galette dough needs to be chilled for at least an hour, and the plums need an hour in the sugar to draw out the juices. The baked galette also needs about an hour or two of cooling to settle the juices. Plan accordingly.

Cut in the butter.

Whisk together 1 1/2 cups all-purpose flour, 1 Tbsp granulated sugar, and 1/4 tsp kosher salt. Add 8 Tbsp cold unsalted butter and work it in until the mixture looks like coarse crumbs with some pea-sized pieces of butter still visible.

In a food processor: pulse the dry ingredients a few times, add the butter, and pulse in short bursts.

By hand: whisk the dry ingredients in a large bowl, then cut the butter in with a pastry cutter or your fingertips.

Those visible butter pieces are what make the crust flaky, so there is no need to work them in all the way.

Add the water and chill.

Add 4-5 Tbsp ice water a little at a time, and stop as soon as the dough holds together when you squeeze a handful.

In a food processor: pour the water through the feed tube with the motor running.

By hand: sprinkle it in one tablespoon at a time and toss with a fork.

Pat the dough into a disk, wrap it, and refrigerate for 1 hour.

Sugar the plums to draw out juices.

Halve and pit 2 lbs Italian prune plums, leaving the halves whole. Toss with 2/3 cup granulated sugar and 1 tsp lemon juice, and let them sit at room temperature for 1 hour. This pulls the juice out before the galette is assembled and keeps the crust from going soggy.

Italian plums taste sweet raw and turn tart in the oven, which is why the sugar runs higher here than it looks like it should.

Make the almond cream.

Beat 1/4 cup unsalted butter, 1/4 cup granulated sugar, 1/2 scant cup almond flour, 1 large egg, 1 1/2 tsp vanilla extract, and 1/2 tsp almond extract on medium speed until combined, then on high for 3 minutes, until light and fluffy.

Drain and coat the plums.

Tip the plums into a colander set over a bowl and let them drain, then blot the halves dry with a paper towel and toss them with 2 Tbsp cornstarch.

Set aside the drained juice. You will reduce it to a syrup later.

Roll out the dough.

Roll the chilled dough into a rough 14-inch circle between two pieces of parchment or on a floured surface. If it's too firm at first, whack it with the rolling pin several times across the dough to soften it and make it easier to roll.

Transfer the dough to a piece of parchment paper that's larger than the dough by about 1 inch. Settle the dough and parchment together into a 9- or 10-inch baking pan, letting both overhang the sides. Refrigerate it until you are ready to fill it, so the rolled dough does not shrink in the oven.

Spread and fill.

Spread the prepared almond cream over the center of the dough in an even layer, leaving a 3-inch border all around. Stand the plum halves on their sides and set them into the cream in a spiral, working from the outside edge in. Sprinkle 2 Tbsp granulated sugar over the plums.

Fold and finish the edge.

Fold the border up over the outer ring of plums in 7 or 8 overlapping pleats, pinching each fold closed. Brush the crust with the egg wash (1 large egg), then sprinkle it with 1 Tbsp coarse sugar.

Bake at 425°F, then 375°F.

Set the dish on the preheated sheet and bake at 425°F for 20 minutes, then lower the oven temperature to 375°F and bake 35 to 40 minutes more, until the crust is deep golden and the juices are bubbling in the center of the tart.

Reduce the juice for the glaze.

Simmer the drained plum juice in a small saucepan until it is thick and syrupy, about 2 to 3 Tbsp. Set it aside to brush over the baked galette.

Cool, then glaze.

Cool the galette on a rack for at least 1 1/2 hours. The juices set as it cools, so a fully cooled galette slices clean. Brush the reduced plum syrup over the fruit and dust with powdered sugar (1 Tbsp powdered sugar) just before serving.

Serve with ice cream or lightly sweetened whipped cream, if you like.