This tart is gorgeous! I would love to go and make one like this right away!

Call it what you will, a plum galette/rustic tart/crostata is a wondrous marvel of simplicity, constructable by anyone who can wield a rolling pin and slice fruit. Just about any dough that's usable for pie crust will do. Nothing fancy to worry about--no elaborate edge crimping, no lattice weaving, no need to weep bitterly if the dough tears while en route to the baking sheet. It's the miracle dessert. Touch it and you'll be healed. (Okay, not really. Forgive my irreverence. Touch it and you'll just really want to eat it.)

When brevity is the name of the game, make a galette. Grab a portion of pie crust dough that's been at the ready, frozen in your freezer; it will defrost quickly while you're gathering and cutting up your fruit. Scrounge around in your fridge for some nice stone fruit that's eager to be eaten up. Plums, peaches, nectarines, etc. --any of those will work. Throw in a few sweet cherries or berries of some kind for added color if you like. Assuming you have a usable chunk of dough laying around, you can probably get one of these babies into the oven in 20 minutes without breaking a sweat.

About the dough:
Any pie dough recipe you like will probably do fine but here's the one I used. This recipe makes enough for two double-crust pies or four single-crust pies; it's good to be able to grab a package of your own ready-to-use dough from the freezer whenever you need it. This recipe makes enough for four galettes--one now and three in the future! Wahooo!

3 and 1/2 cups AP flour, bleached
1 cup cake flour
1 Tbsp. granulated sugar
1 lb. minus 2 Tbsp. (that's 3 sticks plus 6 Tbsp.) of unsalted butter, cut into smallish cubes and put in the freezer for about one hour
1 and 1/2 tsp. fresh lemon juice
3/4 cup ice water, plus more on hand if needed

Combine the two flours, sugar, and salt in the large bowl of a food processor. Pulse until well combined. (Or, do the whole process below by hand in a big bowl with a pastry blender if you prefer. It'll work just as well.)

Scatter the frozen butter cubes over the top of the flour. Pulse the food processor until the cubes are no smaller than peas.

Slowly add the lemon juice and half the water, pulsing just until combined. Continue adding more water until the dough holds together when you test it by pressing a bit of it in your hand. When the dough seems ready to you, dump it into a large regular bowl, or onto a clean flat surface, so you can gather it all up into a ball.

Divide the ball into four equal parts, and shape each one into a flattened disk. Wrap all of the disks individually in plastic wrap and refrigerate however many of them you plan to use within a day or two; freeze the rest.

For the fruit filling:
Use stone fruit, sliced up into large bite-size pieces (plums, peaches, nectarines, apricots will all work; I used about 7 medium-sized plums and a handful of dark sweet cherries that had been pitted and cut into quarters) and, if you like, add some sweet berries for added color.

1/2 cup granulated sugar
2 Tbsp. cornstarch
large pinch of salt
1 egg beaten with two teaspoons of cold water
3-4 Tbsp. sanding sugar or granulated sugar (for top of galette)

source here