Preheat the oven to 375 degrees Fahrenheit.
Add the olive oil to a skillet over a medium high temperature, and saute the leeks for about 5 minutes, until wilted. Set aside, and allow them to cool.
In a large mixing bowl, add the eggs, cream, and milk. Beat well.
Now add the salt, pepper, lemon juice and zest, and chopped thyme to the egg mixture. Blend together well with a whisk or fork.
Poke a few holes in the bottom of the quiche pastry with a fork. Add the leeks to the bottom of the quiche.
Pour the egg mixture over the leeks.
Dot with the crumbled feta cheese.
Top with Romano cheese.
Bake for 30 to 40 minutes or until firm all the way through the middle.
Can be eaten warm, cold, or at room temperature.