Preheat your oven to 350 degrees. Spray a pie dish with oil.: The oven should be fully warmed so the custard begins to set evenly the moment it goes in, producing a tender interior and lightly golden edges. You will notice a faint warmth and an even ambient heat when it is ready. If you skip preheating, the quiche may bake unevenly, leaving the center undercooked while the edges overbake. Common troubleshooting involves using an oven thermometer to confirm the true temperature, because oven dials can be inaccurate.
Steam the chopped asparagus & leeks in the microwave with 1 tablespoon water until tender crisp and green but not mushy, about 2 1/2 to 3 minutes.: A light coating of cooking spray prevents sticking and helps the quiche come out cleanly. The sprayed surface looks uniformly glossy and will release the quiche without tearing. If you over spray, excess oil can pool and make the bottom greasy; pat away any pooling with a paper towel before adding the ingredients. Using a glass or ceramic pie dish will influence baking time slightly, so watch for visual doneness cues.
Evenly spread the asparagus & leeks in the dish and top it evenly with the crumbled feta.: Steaming preserves the bright color and fresh bite of asparagus and softens the leek without making them watery. You'll hear a gentle hiss from the steam and see the vegetables turn a more vibrant green. Over steaming results in limp, dull colored vegetables that sink into the custard texture, so err on the side of undercooking if unsure. If your microwave is powerful, reduce the time slightly to avoid overcooking.
Make the custard mixture by whisking together the milk, half and half, eggs, salt, black pepper. Pour the custard into the dish, top with dill & za’atar and bake 35 to 40 minutes, until the center is set.: Arrange the steamed vegetables in a single, even layer so each bite includes both texture and flavor. The scattered feta will melt slightly into the vegetables while still keeping its crumbly character, lending salty pockets. If you mound the vegetables, the custard may not penetrate evenly, producing dense areas. Take a moment to distribute the feta so no single area becomes overwhelmingly salty.
Cut the quiche into 6 pieces and serve.: Whisk until the mixture is smooth and slightly frothy, which helps incorporate air and yields a lighter set. The mixture should look homogenous, pale, and slightly glossy. A common misstep is underwhisking, which can leave streaks of egg white or uneven texture in the finished bake. Use a whisk and a bowl large enough to avoid splashing, and taste a tiny bit to check seasoning before pouring.
Pour the custard into the dish, top with dill & za’atar and bake 35 to 40 minutes, until the center is set: As the quiche bakes, you will see the custard begin to puff slightly and the edges turn a soft golden color, while the center should still jiggle gently but not look liquid. The aroma will shift to a warm, eggy scent accented by herb and feta . If it browns too quickly, tent loosely with foil to prevent overbrowning while allowing the center to finish cooking. Incomplete set indicates it needs more time; check after 5 additional minutes rather than removing too early.
Cut the quiche into 6 pieces and serve: After a brief rest, the quiche will firm up and slice cleanly, revealing layers of green vegetables and creamy custard. The surface should have a gentle, silk like appearance with no visible wet custard. If you slice too soon, the pieces may be sloppy and lose shape. Let it rest for about 10 minutes so the structure stabilizes and the flavors meld.