Notes:
This dough can be made in advance and frozen. Also, if you prefer a more piquant flavored pie, add any or all of the following: a few crushed thyme leaves added to the custard, a pinch of nutmeg (recommended), or two tablespoons white wine added to the onions.
Tips:
Substitute 10 coarsely ground sun-dried tomatoes in oil for the pesto. Or use tomatoes for half the pie and pesto for the other half. You can also mix some of the pesto into the custard if desired.