This savory galette is a great way to turn winter squash into supper. Since you don't have to transfer the dough into a pie plate or make neat edges, it's a great way to practice working with pie dough. Serve this galette as a vegetarian main or side dish or as an appetizer for a celebratory meal.
Whisk the flour and salt in a mixing bowl until well blended. If you do not own a pastry cutter (also called a blender) to cut the butter into the flour, try this: use a box grater to grate the butter, working quickly to prevent warming it with your hands. Add the butter to the flour mixture and use your hands to toss and separate the grated butter and coat the pieces with the flour.
Dribble the water over the flour mixture and use a fork to gently blend it into the flour to make a rough dough. Tip the dough onto the counter and use a dough scraper (also called a bench knife) to gather it together. Press each piece into a disk, wrap in plastic wrap and chill while you prepare the filling. (You can make this dough up to 2 days in advance.)
Preheat the oven to 400 degrees F. Toss the squash and onion with the olive oil, mustard, sage, salt and pepper and arrange on a sheet pan in a single layer. Roast until the onion is translucent and the squash is fork tender but has not browned, about 20 minutes. Set aside to cool.
On a lightly floured countertop, roll out the dough into a circle about 14 inches across and 1/4 inch thick. Leaving a 3-inch edge, transfer the filling to make an even layer of squash and onions in the center of the dough. Fold the edges over the filling, pleating the dough to form a wide border. Brush the dough with the egg wash, if using.
Slide the galette onto an inverted, ungreased baking sheet. Bake until the crust is deeply golden brown, about 30 minutes. Transfer to a serving platter.
Copyright 2021 Lynne Curry