1-For the first step, prepare the dough by pulsing the flour, sugar, and salt together in a food processor until combined. Add the cubed cold unsalted butter and pulse until the mixture forms pea-sized pieces. Gradually add the ice water, one tablespoon at a time, until the dough begins to come together, then remove it from the processor, shape it into a ball, flatten it into a disc, wrap it in plastic wrap, and chill it in the refrigerator for 30-45 minutes.

2-Next, preheat the oven to 400 degrees Fahrenheit and get the grape filling ready. Mix the halved grapes, lemon juice and zest, vanilla, brown sugar, cornstarch, and optional spices in a bowl, and let it rest for 5-10 minutes to thicken. Roll out the chilled dough on a floured surface into a 12-inch circle and transfer it to a baking sheet lined with parchment paper or a silicone mat.

3-Spoon the grape mixture onto the dough center, using a slotted spoon to leave behind any excess juices, then fold the edges up and over the filling. Brush the dough edges with the egg wash and sprinkle with turbinado sugar if desired. Bake for 30-40 minutes until golden, and let it cool a bit before serving.