Step 1: To make the dough, cut the butter into 1″ cubes and chill in the freezer for 10 minutes. Combine the kefir cream and salt in a small bowl and freeze for 10 minutes.
Step 2: Spread the flour out onto your work surface into a rectangle about 1/3″ deep. Scatter the chilled butter cubes over the flour. Toss a little of the flour over the butter so that your rolling pin won’t stick, and then begin rolling the butter into the flour. When the butter starts flattening into long, thin pieces, use a bench scraper to scoop up the sides of the rectangle so that it is again the size you started with. Repeat the rolling and scraping three or four times; the dough will be a shaggy pile with visible ribbons of butter throughout.
Step 3: Make a well in the centre of the dry ingredients and pour all of the chilled kefir cream into the well. Using the bench scraper, scoop the sides of the dough onto the centre, cutting the cultured cream into the dough. Keep scraping and cutting until the dough is a shaggy mass, then shape the dough into a rectangle about 10″ by 14″. Lightly dust the top with flour. Roll out the rectangle until it is half again as large, then scrape the top, bottom, and sides together to the original size and re-roll. Repeat three or four times until you have a smooth, cohesive dough. You should have a neat rectangle measuring about 10″ by 14″. Transfer the dough to a large baking sheet, cover with plastic wrap, and refrigerate for about 1 hour.
Step 4: In a large bowl, combine the cherries and lemon juice. Set aside.
Step 5: Divide the dough into two equal portions if making large galettes or twelve equal portions if making small galettes. To roll a circle from what is roughly a square, start with the dough positioned as a diamond in front of you, with the ends of the rolling pin parallel to two points of the square. Roll from the centre toward each end, only flattening the centre, not the two points that are nearest to and farthest from you (at top and bottom); leave those two points thick. Now turn the dough so that the flattened-out corners are at the top and bottom. Again, roll from the centre toward the points nearest to and farthest from you, again stopping short of both the top and bottom. Now you should have a square that has little humps between the pointy corners. Roll out the thicker areas and you will begin to see a circle form.
Step 6: Keep rolling until the dough is a little more than 1/8″ thick for large galettes (each circle should be about 14″ in diameter) and a little thinner for individual galettes (each circle should be 6″ to 7″ in diameter). Fold the large circles into quarters, transfer each one to a baking sheet, and unfold. Transfer the small circles to baking sheets without folding. Refrigerate the circles until firm, about 10 minutes.
Step 7: Fill the centre of each dough circle with some of the cherries, leaving a 2″ border uncovered on the large galettes and a 1″ border uncovered on the small galettes. Fold in the sides of the circles to partially cover the fruit, being sure not to leave any valleys where the fruit juice can leak out.
Step 8: Add 2 tablespoons of the granulated sugar over the fruit for each large tart and 1 teaspoon of sugar for each small tart. Refrigerate until firm, about 10 minutes. While the galettes are chilling, preheat the oven to 375°F.
Step 9: For the egg wash, in a small bowl, whisk together the egg yolk and heavy cream. Brush the egg wash over the pastry edges, then top the pastry with the Turbinado sugar.
Step 10: You can bake the galettes immediately or, dividing them evenly, refrigerate, unwrapped, for up to 2 hours. (Or you can skip the egg wash and sugar, wrap the galettes airtight, and freeze them for up to 2 weeks. When ready to bake, remove from the freezer, brush with the egg wash and dust with Turbinado sugar, and bake straightaway. Add 10 minutes to the baking time.)
Step 11: Bake the galettes until the crust has visibly puffed and baked to a dark brown and the juice from the fruit is bubbling, 45 to 60 minutes for large galettes and 40 to 50 minutes for small galettes. Rotate and switch the baking sheets between the racks halfway through baking. If the pastry is browning too quickly, reduce the oven temperature to 350°F or place aluminum foil over the tops of the galettes. Remove from the oven and serve hot, or let cool on a wire rack and serve warm or at room temperature. Galettes will keep at room temperature for up to 2 days.
Makes two 12″ or twelve 4″ galettes
Reprinted with permission from Chad Robertson’s Tartine Book No. 3 (2013 Chronicle Books).