Balsamic Caramelized Onion Tart

I never use to buy puff pastry dough. I didn't understand the need for it. Now, especially during this busy holiday season, I keep 3-4 boxes stocked in my freezer at all times. Short on time for dinner? Defrost a puff pastry sheet, top with thinly sliced vegetables, like beets or carrots, add a drizzle of olive oil maybe a dollop of goat cheese and you have an instant dinner. Or create a quick pizza by spreading out some simple tomato sauce over top, add some cheese, maybe a little meat. And there you have it, a perfect flaky pizza. 

Puff pastry also works perfectly for that appetizer you promised you would bring to the party, but really have no time to make. So what I am saying, is in this busy holiday craze, go buy yourself some puff pastry. Cut your cooking time by half and enjoy the holidays with friends and family. 

serves 4-6

1/4 cup extra-virgin olive oil
3 large onions, finely sliced
2 rosemary sprigs
1/2 cup balsamic vinegar
3/4 cup sugar (brown sugar works well too)
Pinch of sea salt flakes
1 large sheet of puff pastry (defrosted, but not warm) 
1 egg, for egg wash
4 thyme sprigs

goat cheese
ricotta cheese

In a large pot, add olive oil and heat over medium-high. Add the onions, stirring occasionally, for about 15 minutes. You want them golden brown. Either tie the rosemary together with twine, or if you don't mind loose rosemary leaves, leave untied. Add the rosemary, turn heat to low and cook for 5 minutes. Increase the heat back up to medium-high and add the brown sugar. Cook for 5-7 minutes without stirring until the sugar has melted into the onions. Add the balsamic vinegar and simmer over low heat for another 5-7 minutes. Stir occasionally until the jam is fragrant and thick. Add a pinch of flaky salt and let cool. 

Preheat the oven to 425 degrees. Line a baking sheet with parchment paper and set aside.

Using two small bowls (about 6"), cut 2 rounds of pastry and place on baking sheet. Take a sharp knife and carefully score, making sure to not go all the way through, a 1/2" border around both pastry cut-outs. Prick the center with a fork, a few times. Brush the border with egg wash. Starting with 2-3 tablespoons of balsamic caramelized onion jam, fill the center and evenly spread out, avoiding the border. Add more if desired. (Note, at this point you could put a dollop of goat cheese or ricotta cheese right in the center). Place 2 thyme sprigs onto top of each pastry. 

Bake for 20-23 minutes until puffed and golden. Let cool slightly before serving. The longer you let it cool, the jam will become gel-like, making it easier to slice.