Jersey Milk Onion Tart

**Make the Crust:** In a medium bowl, whisk together flour and salt. Cut in the cold butter using a pastry blender or your fingers until the mixture resembles coarse crumbs. Gradually add ice water, 1 tablespoon at a time, mixing until the dough just comes together. Flatten into a disk, wrap in plastic wrap, and refrigerate for at least 30 minutes.

**Caramelize the Onions:** Heat olive oil in a large skillet over medium-low heat. Add sliced onions, thyme, salt, and pepper. Cook, stirring occasionally, for 30-40 minutes, or until the onions are deeply caramelized and golden brown. Stir frequently toward the end to prevent burning. Remove from heat and set aside to cool slightly.

**Preheat Oven:** Preheat oven to 375°F (190°C).

**Roll and Assemble:** On a lightly floured surface, roll out the chilled dough into a 12-inch circle. Carefully transfer the dough to a 9-inch tart pan, pressing it into the bottom and up the sides. Trim any excess dough. Dock the bottom of the crust with a fork to prevent it from puffing up during baking.

**Blind Bake:** Line the tart crust with parchment paper and fill with pie weights or dried beans. Bake for 15 minutes. Remove the parchment paper and weights, and bake for another 5 minutes, or until the crust is lightly golden.

**Prepare the Filling:** In a medium bowl, whisk together Jersey milk, eggs, salt, pepper and nutmeg.

**Assemble and Bake:** Spread the caramelized onions evenly over the pre-baked tart crust. Sprinkle with Gruyere cheese. Pour the milk and egg mixture over the onions and cheese.

**Bake:** Bake for 25-30 minutes, or until the filling is set and the top is golden brown. A knife inserted into the center should come out clean.

**Cool:** Let the tart cool in the pan for at least 15 minutes before slicing and serving.