A note on the egg-to-liquid ratio: I used a ratio I found in a number of places, attributed to Julia Child, which has you put the eggs in a liquid measuring cup and then add however much liquid (cream, half-and-half, or milk) to bring the ratio to 1/2 cup of egg-liquid mixture per egg. So, for 3 eggs, you would put the eggs in a measuring cup and then add enough liquid to bring the mixture to 1 1/2 cups. Technically, that means 3 eggs should use a little less than 1 cup, but I used these measurements for simplicity’s sake — especially because another Julia Child recipe I’ve seen in a number of places calls for 3 eggs and far more cream, about 1 1/2 cups. You can up the liquid to that amount if you like, for a softer quiche.
That said, quiche is endlessly customizable once you have a trusty egg-to-liquid ratio. Another favorite of mine is leek, bacon, and Gruyere — just crisp up about 2-3 ounces of bacon (4-6 rashers) in the oven or on the stove, saute about 1 cup of sliced leeks in a few tablespoons of butter (or reserved bacon fat!) until tender and caramelized (about 15 minutes), and use these in place of the asparagus and green peas, above. Omit the goat cheese.