Position a rack in the center of the oven and heat the oven to 400°F. Let the dough sit at room temperature until pliable, 10 to 15 minutes.
Roll the dough between 2 sheets of lightly floured parchment paper into a 14-inch round, loosening the parchment from the dough occasionally and adding a bit more flour if it sticks. Transfer on the parchment to a large rimmed baking sheet; remove and discard the top sheet of parchment.
In a small bowl, whisk the egg and cream.
In a large bowl, whisk the flour, granulated sugar, 1/2 tsp. of the cardamom, and 1/8 tsp. salt. Add the peaches, 1 Tbs. of the lemon juice, and the vanilla; toss gently to combine.
Leaving a 2-inch border, spoon the peach mixture and any juice over the dough. Fold the edge of the dough up and over the filling. If the dough is sticking to the parchment, refrigerate it for 5 to 10 minutes, and then continue folding. Brush the folded dough with the egg wash and sprinkle the turbinado sugar all over the galette.
Bake, rotating the baking sheet once halfway through, until the crust is golden brown, 40 to 50 minutes. Let cool on a rack for 15 to 20 minutes.
Meanwhile, in a small saucepan, bring the honey, the remaining 1/4 tsp. lemon juice, the remaining 1/4 tsp. cardamom, and 1/8 tsp. salt to a simmer. Cook for 1 minute, and then remove from the heat. Let stand 1 minute. Sprinkle the warm galette with the hazelnuts, and drizzle with the warm honey. Serve warm or at room temperature with the yogurt, if using.
nutrition information (per serving):
300, Fat Calories
15, Saturated Fat
9, Polyunsaturated Fat
1, Monounsaturated Fat
Photo: Scott Phillips