01 - Preheat oven to 375°F.
02 - In a bowl, mix flour and salt. Cut in cold butter until mixture resembles coarse crumbs. Add ice water one tablespoon at a time, mixing until dough just holds together. Shape into a disk, wrap in plastic, and refrigerate for 20 minutes.
03 - Roll out dough on a floured surface to fit a 9-inch tart pan. Press dough into pan and trim excess. Prick base thoroughly with a fork. Line with parchment paper and fill with pie weights or dry beans.
04 - Bake crust for 15 minutes. Remove weights and parchment paper, then bake for an additional 5 minutes until lightly golden. Set aside while preparing filling.
05 - Heat olive oil in a skillet over medium heat. Sauté asparagus and zucchini for 3-4 minutes until just tender. Add spinach, scallions, and peas; cook for 1-2 minutes until spinach wilts. Remove from heat and let cool slightly.
06 - In a bowl, whisk eggs, heavy cream, whole milk, salt, pepper, and nutmeg until thoroughly combined. Stir in half of the grated cheese.
07 - Spread sautéed vegetables evenly over the partially baked crust. Pour egg custard mixture over vegetables. Sprinkle remaining cheese evenly on top.
08 - Bake quiche for 30-35 minutes until filling is set and no longer jiggles in the center, and the top is golden brown.
09 - Allow quiche to cool for 10 minutes before slicing and serving. Serve warm or at room temperature.