Preheat oven to 350°.
Sprinkle a thin layer of shredded cheese over the bottom of the pie crust.
Dice onions and tomatoes, cut broccoli crowns and mushrooms into bite-size pieces, and break asparagus spears into 1/2” pieces.
In a large saucepan or Dutch oven, sauté the onions, broccoli, asparagus, and mushrooms until the onions are translucent and the broccoli and asparagus are bright green. Don’t overcook. Add the tomatoes at the end for about 1 or two minutes.
Remove from heat and add loosely to the pie crust. Don’t pack tightly, but fill in as much as you want. The more vegetables you have, the less room you’ll have for the egg mixture. If you want more of the egg mixture, then add fewer vegetables. Adjust to suit your taste.
In a mixing bowl/blender whip together the eggs and milk. Pour the mixture into the pie crust until it covers the vegetables. You may have some mixture left over depending how many vegetables you’ve used.
Place pie crust in oven on center rack. Bake uncovered for approximately 30 minutes.
Add a thin layer of shredded cheese to the top of the quiche for the last 5 minutes. Cut into wedges and serve.
Spätlese (a semi-sweet white German wine) goes great with this dish. Fresh bread/rolls are also a nice compliment, as is fresh corn on the cob.