Flaky Gruyère Onion Galette The Ultimate Recipe for Entertaining

Instructions:

1. Make the Pastry: Pulse flour and salt in a food processor or mix in a bowl. Cut in the cold, cubed butter until pea-sized crumbles form. Gradually add ice water until the dough just comes together. Form into a disk, wrap tightly, and chill for at least 1 hour.
2. Caramelise the Onions: Melt the 2 tablespoons of butter and olive oil in a large, heavy-bottomed skillet over medium-low heat. Add the sliced onions and salt. Cook slowly, stirring every 10 minutes, for 30–35 minutes until they are deep golden brown and jammy.
3. Finish the Filling: Stir the sugar, balsamic vinegar, and fresh thyme leaves into the cooked onions. Cook for 2 more minutes, then remove from the heat and allow the mixture to cool completely.
4. Roll the Dough: On a lightly floured surface, roll the chilled pastry into a rough 14-inch circle. Carefully transfer the dough onto a baking sheet lined with parchment paper.
5. Assemble the Tart: Spread the cooled onion mixture evenly over the dough, leaving a generous 2-inch border clear around the edge. Sprinkle the grated Gruyère cheese evenly over the onion layer.
6. Fold the Edges: Fold the exposed pastry border up and over the filling, pleating it roughly every inch to create the rustic 'crown' shape of the galette.
7. Egg Wash & Bake: Whisk the egg with 1 teaspoon of water to create an egg wash. Brush the exposed crust generously with the wash. Bake in an oven preheated to 400°F (200°C) for 45–50 minutes, or until the crust is deep golden brown and the cheese is bubbling.
8. Rest and Serve: Sprinkle the hot crust with flaky sea salt and freshly ground black pepper. Let the galette rest on the tray for 10 minutes before slicing and serving warm or at room temperature.