1 stick of butter
2 ½ pounds of mild onions, sliced into thin half-moons
6 tablespoons flour
1 cup cream (the traditional recipe uses sour cream, but we like real cream better)
1 tablespoon caraway seeds
2 teaspoons salt
¾ cup of sliced pancetta or bacon, if desired (our version is vegetarian)
1 sheet of puff pastry
Melt the butter in a heavy-bottomed skillet and add the onions. Cover with a tightly-fitting lid and steam gently (on low heat) for 20 minutes, stirring only occasionally. Remove the pan from heat and allow to cool with the lid on.
Preheat your oven to 375°.
Roll out puff pastry thin enough to line the bottom and edges of a half-sheet pan (18 by 13 inches) or similarly-sized square pan. Mix the eggs, cream, salt, and caraway seeds. Sift in the flour and stir gently to combine. Fold in the onions and spread the mixture evenly over the puff pastry. Sprinkle with the bacon or ham (if you’re using). Bake for approximately 30 minutes, until golden.