Blueberry Skillet Galette

Directions

1. Make the dough: Place the flours, sugar, and salt in the bowl of a food processor and pulse to combine. Add the cold butter and pulse, until the mixture forms pea-sized bits. Add the egg to the food processor and pulse to incorporate. Combine the vinegar and ice water in a measuring cup. In a slow stream, add the vinegar-water mixture while pulsing, stopping once a cohesive dough forms. To test, open the lid and squeeze some of the dough in your hand—if it holds together, it is ready. If the dough still crumbles, add just a bit more vinegar-water mixture and pulse a few more times. (You may end up using slightly less of the vinegar-water mixture.)
2. Form the dough and chill: Empty the dough out onto a long section of cellophane and flatten to form a disk. Wrap tightly and refrigerate for at least 20 minutes to let the dough rest.
3. Make the filling: Combine all filling ingredients in a large bowl, stir to combine, and macerate for at least 20 minutes.
4. Remove the dough from the refrigerator 10 to 15 minutes before attempting to work it. Lightly flour an 18-inch long sheet of parchment. Place the pastry disk in the center, lightly flour it, then use the cellophane it was wrapped in, laid on top. Roll the pastry into a rough circle that’s about ⅛-inch thick, peeling the cellophane or parchment away and re-flouring at intervals as needed. If the dough becomes smeary or floppy at any point, transfer to a sheet pan on the parchment and refrigerate until cool enough to handle. Use the sauté pan as a gauge for the needed size—the dough should end up approximately 15 inches in diameter.
5. Preheat the oven to 400ºF. Remove the cellophane from the dough. Transfer it onto the parchment into the sauté pan, gently pressing the pastry to conform to the pan base. Empty the blueberry mixture into the pan. Peel the pastry away from the parchment, draping and crimping pastry onto the filling. Use slightly wetted fingertips to press the pleats as you go.
6. Paint the pastry surface with egg wash, then sprinkle it with Demerara sugar. Refrigerate for 20 minutes.
7. Bake the galette for 40 minutes. Cover any pastry from browning too much with small segments of foil. Bake for another 15 minutes, or until the filling bubbles. Cool the galette in its pan for 45 to 60 minutes so the filling can set. Cut into wedges and serve with crème fraîche or vanilla ice cream.