Prepare the Crust:

• In a large bowl, whisk together the flour, sugar, and salt.

• Add the cold, cubed butter and use a pastry cutter or your fingers to work it into the flour until the mixture resembles coarse crumbs with pea-sized pieces of butter.

• Gradually add 4 tablespoons of ice water, stirring with a fork until the dough starts to come together. Add more water if necessary.

• Turn the dough out onto a floured surface, knead it gently into a ball, then flatten it into a disk. Wrap in plastic wrap and refrigerate for at least 30 minutes.

Prepare the Filling:

• While the dough chills, combine the apricots, cherries, sugar, cornstarch, lemon juice, and vanilla extract in a bowl. Toss the fruit to coat evenly and set aside.

Assemble the Galette:

• Preheat the oven to 375°F (190°C). Line a baking sheet with parchment paper.

• Roll the chilled dough out into a 12-inch circle on a floured surface.

• Transfer the dough to the prepared baking sheet. Spoon the fruit mixture into the center, leaving a 2-inch border around the edges.

• Fold the dough edges over the fruit, creating a rustic border.

Brush and Bake:

• Beat the egg in a small bowl and brush it over the exposed dough. Sprinkle with coarse sugar if desired.

• Bake for 40-45 minutes, or until the crust is golden and the fruit filling is bubbling.

Cool and Serve:

• Let the galette cool for at least 10 minutes before slicing and serving.