Caramelized onion tart

This is kind of the opposite of the last post, at least in my food world. It's very rich and indulgent. Luckily, since it's so rich, you don't want to eat a lot of it. As you can see above, I just had a small piece of this tart with a big salad and a bunch of asparagus for a very nice meal. Jon and I managed to make it last two dinners and one lunch. If you know Jon, you know that is quite a feat.

Caramelized onion tart (from Jeanne Lemlin's Vegetarian Classics)
If you caramelize the onions the night before, this comes together very quickly.

1 sheet frozen puff pastry
1 tbsp olive oil
2 lb onions, thinly sliced (about 9 cups)
2 large eggs
1/2 cup heavy cream
Dash cayenne pepper
1/2 tsp salt
1/2 cup grated Swiss cheese (we used Ementaler)

Let the puff pastry thaw for at least 30 minutes on the counter or a few hours in the fridge. You want it to be cool but not frozen when you work with it.
While you're waiting on the puff pastry, prepare the onions. Heat the oil in a large stockpot over medium heat. Add the onions and partially cover the pot. Cook, stirring often, for about 40 minutes or until the onions are a deep caramel color and very soft. You'll want to turn down the heat as the onions begin to soften so they can cook slowly and get all nice and brown. Scrape the bottom of the pot often to prevent sticking. Marvel at how much their volume decreases. Let the onions cool.
Lightly butter a tart pan or pie dish. On a lightly floured surface roll the puff pastry into an 11-inch square (just a little thinner than its starting size.) Press into the buttered pie dish and tear off the bits than hang over unless you want puff pastry charcoal at the end.
Beat the eggs in a large bowl. Beat in the cream, cayenne, and salt. Stir in the cheese and onions. Spoon the mixture into the pie dish. It might look underfilled, but it will fill out as it bakes. Bake 30-35 minutes at 425, until the custard is set and the crust is a deep gold. Ours looked like this:
Cool on a wire rack for 15-20 minutes before serving.