To make the dough, combine flour, sugar, cornmeal, and salt in a processor; pulse 2-3 times. Add butter and pulse 4-5 times, or until mixture resembles coarse meal. With the processor running, slowing pour the buttermilk through the chute, processing until the dough forms a ball. Remove the dough ball and adhere any remaining pieces of dough to it, then wrap in plastic wrap or parchment paper. Refrigerate for at least 45 minutes before rolling out.

Center a rack in the oven and preheat to 350 degrees F.

In a medium bowl, combine the sliced peaches, sugar, cornstarch, vanilla extract, almond extract, if using, and cinnamon. Add a quick squeeze of fresh lemon juice. Gently stir until cornstarch disappears and the peaches are well coated. Set aside.

Remove the galette dough from the refrigerator and place on a sheet of parchment paper. Starting at the center of the dough, roll out, forming a 14-inch-wide circle. Place the dough with parchment paper on a baking sheet.

Place the peach filling on top of the dough, leaving a 2-inch border. Fold the dough border gently over the berries, overlapping where necessary and pressing gently to adhere the folds.

In a small bowl, beat the egg and water together with a fork. Lightly brush the edge of the dough with the egg wash. In a small bowl, combine the turbinado sugar and cinnamon. Sprinkle the mixture evenly over the dough border.

Bake the galette for 45-55 minutes, or until the crust is golden brown. Transfer the baking sheet to a wire rack to cool to room temperature before slicing.

Drizzle with honey, if desired. Cut the galette into pieces and serve. I recommend serving with vanilla ice cream or whipped cream.