Triple Threat Onion Galette Recipes

Steps:

• Prepare the dough: In a large bowl, whisk together flour, sugar, 1 1/2 teaspoons kosher salt and 1 1/2 teaspoons black pepper. Add butter and 1 cup grated Gruyère to the flour mixture and toss to coat. Using your fingertips, pinch the butter and cheese into the flour to make pebble-size pieces. Drizzle in the ice water and stir to make a shaggy dough. Dump the dough onto a large sheet of plastic wrap and knead a few times to combine. Wrap in plastic and refrigerate for at least 4 hours.
• Prepare the onions: In a large skillet, melt the butter over medium-high heat. Add onions and thyme sprigs, season with 1 teaspoon salt and 1/2 teaspoon pepper and cook, stirring occasionally, until the onions are translucent and lightly golden on the edges, 20 to 25 minutes. Reduce the heat to medium, add broth and sherry and cook until the onions are browned and the liquid has mostly evaporated but the mixture is still saucy, 16 to 18 minutes. Transfer to a bowl and set aside to cool for at least 30 minutes.
• Heat the oven to 375 degrees. Roll the dough into a 13-inch round on a sheet of parchment. Spread the cooled caramelized onions on the dough, leaving a 1- to 2-inch border. Fold the edges in, over the onions, transfer to a baking sheet and bake until the dough is golden brown and some of the onions have browned on the edges, 40 to 50 minutes, rotating the galette halfway into the baking process.
• Remove galette from the oven and sprinkle remaining 1/3 cup grated Gruyère on the crust. Bake another 5 minutes to melt the cheese. Remove and let rest for 10 minutes before slicing. Top with remaining thyme leaves, for garnish.

Steps:

• Dough:
• Whisk sugar, salt, and 1½ cups flour in a medium bowl to combine. Add butter and toss to combine. Using your hands and working quickly, rub and smash butter into flat, irregular pieces (be careful not to overwork; you don't want to soften the butter too much).1 Drizzle ⅓ cup cold water over and mix with a rubber spatula, smashing in butter, until dough mostly comes together-it will be dry and shaggy.
• Turn out dough onto a lightly floured surface. Working quickly and using a rolling pin and your hands, press dough together to form a mass. Roll dough into a rough square about ½" thick. Fold in half into a rectangle, then once again to make a small square. Press down on the dough with rolling pin to make it hold together. Roll dough out once more to make a rough square about ½" thick. Repeat folding process, taking your time to make it neat as this will be your final fold. Using rolling pin, gently flatten dough, rotating as needed, to make a 6"-diameter disk.
• Dust surface with more flour and roll disk into a 14"-diameter circle or oval about ⅛" thick. Fold dough in half, then in half again to make a rough triangle (this will make it easier to move). Slide onto a parchment-lined baking sheet and unfold. Chill while you make the filling.
• Do Ahead: Dough can be made 3 days ahead. Wrap 6" disk tightly and chill until ready to roll out.
• Assembly:
• Place a rack in middle of oven; preheat to 375°F. Heat 3 Tbsp. butter in a medium skillet over medium until foaming, about 1 minute. Reduce heat to medium-low; add onion, garlic, and 1 tsp. Diamond Crystal or ½ tsp. Morton salt, and stir to combine. Cover and cook, stirring occasionally, until onion is tender and just beginning to brown, 6-8 minutes. Uncover and continue to cook, stirring occasionally and adding a splash of water if onion begins to stick, until golden brown in spots, about 5 minutes more. Transfer onion mixture to a plate; reserve skillet.
• Melt remaining 1 Tbsp. butter in reserved skillet (no need to wipe out) over medium heat. Remove from heat and add scallions and remaining ½ tsp. Diamond Crystal or ¼ tsp. Morton kosher salt. Toss scallions until coated in butter.
• Remove dough from refrigerator and, using a small offset spatula or a spoon, spread mustard in a thin layer over dough, leaving a 1½"-2" border around the edges. Scatter onion mixture over mustard and sprinkle with Parmesan; season with pepper. Cutting from edge of dough to the start of the mustard and filling, make slits in border of galette at 2"-3" intervals. Fold flaps up and over filling, slightly overlapping. Scatter scallions over. Bake galette until crust is deep golden brown and scallions are lightly charred, 45-50 minutes. Using parchment paper, slide galette onto a cutting board and cut into wedges.
• Do Ahead: Onion can be cooked 3 days ahead; transfer to an airtight container, then cover and chill. Galette can be assembled 1 hour ahead; chill.