Quiche Sardou

Ingredients

• 1/2 cup (1 stick) chilled unsalted butter, cut into cubes
• 1/8 teaspoon kosher salt
• 1 1/4 cups all-purpose flour, plus more for surface
• 1 large egg yolk
• 5 ounces baby spinach (about 4 packed cups)
• 2 tablespoons unsalted butter
• 1 medium onion, thinly sliced
• 1/2 cup frozen artichoke hearts, thawed, coarsely chopped
• 1 teaspoon kosher salt
• 1/2 teaspoon freshly ground black pepper
• 4 large eggs
• 2/3 cup heavy cream
• 2/3 cup whole milk
• A 9-9 1/2-inch round fluted tart pan (1 inch deep) with removable bottom; pie weights or raw rice