"Apricots and cherries are two stone fruits that have great affinity for each other and for almonds. Even less than perfect apricots will do here, as they will sweeten and their flavor will deepen as they bake."
Remove the pastry from the freezer and place it on a baking sheet lined with parchment. Leave it to thaw while you prepare the fruit, but don’t keep it out of the freezer for too long. It will thaw quickly, and it is easiest to handle if it’s cold. You want it just soft enough so that you can manipulate it.
Combine the cherries, apricots, slivered almonds, almond extract and 2 tablespoons of the sugar in a large bowl and gently toss together.
Sprinkle the almond powder over the pastry, leaving a 2- to 3-inch border all around. Place the fruit on top. Fold the edges of the dough in over the fruit, pleating the edges as you work your way around the fruit to form a free-form tart that is roughly 9 inches in diameter. Place in the freezer on the baking sheet for 45 minutes to an hour. This helps the galette maintain its shape.
Meanwhile, preheat the oven to 350 degrees. Remove the galette from the freezer. Brush the exposed edge of the pastry with the egg wash. Combine the remaining tablespoon of sugar and 1/4 teaspoon cinnamon and sprinkle over the fruit and the crust. Place in the oven and bake 1 hour, until the fruit is bubbly and the juice is running out and caramelizing on the parchment. Remove from the oven and allow to cool for at least 15 minutes. Serve hot or warm or at room temperature.
Advance preparation: You can assemble this through Step 3 and freeze it for up to a month. Once it is frozen, double-wrap in plastic.