Baking at the wrong temperature
Many pie recipes call for higher baking temperatures, up to 425 F, but quiche requires a different approach. A high temperature could ruin your carefully crafted custard tart. Some quiche recipes call for baking at 350°F to 400°F, but you should avoid it. This dish requires a lower temperature range. If you've ever noticed your quiche filling puffing up (almost like a soufflé), your oven was probably too hot. Instead of being too eggy, your filling should be velvety.
325 F is the ideal oven temperature for baking quiche. If you blind-baked your crust at 350 degrees Fahrenheit, remember to reduce the oven temperature before baking the filling. This lower temperature will result in a tender, creamy custard rather than a dry, overbaked one. This will also help prevent the top from browning or burning before the center is cooked.