If using a cast iron skillet, lightly coat the bottom and sides of the pan with olive oil. Heat pan over medium-high heat and let oil get hot (which also makes the oil easier to coat the pan, thereby requiring you to use less oil!). While this is heating but after you’ve coated the pan well, spread your vegetable mixture over the bottom of the pan evenly. Then, quickly give your egg mixture one last stir to mix anything that might have settled, and pour the mixture evenly over the veggies. Immediately remove the cast iron skillet from the heat. This step cooks the first layer of the egg mixture, creating a “pseudo-crust” that, in my opinion, makes one not miss the pastry crust of the quiche as much!