If you can’t find fresh tarragon you can use crushed fennel seeds (about 1/2 tsp) and sprinkle over the tart. to replace the tarragon.
Makes 9 – 12 appetizer sized squares
Ingredients
2 tbsp olive oil
4 cups sliced onions, sliced root to top into 1/4 inch slices (about 2 large onions)
1 tbsp brown sugar
2 tbsp balsamic vinegar
1/2 tsp salt, or to taste
1/2 tsp ground pepper
8 oz frozen puff pastry, (defrosted in the fridge for a couple of hours)
3 oz chilled brie, rind removed and diced
3 oz gorgonzola or other blue cheese, diced
2 tbsp chopped fresh tarragon (or 1/2 tsp or so of crushed fennel seeds)
Directions
Heat the oil in a large deep pan on medium heat. Add onions and cook for about 10 minutes or until wilted and stating to brown. Add the sugar, vinegar, salt and pepper.
Reduce the heat and cook gently for 25 to 30 minutes or until richly caramelized.
Add a little water if the onions look like they’re starting to dry out. Cool.
Roll the pastry into a 10 by 14 inch rectangle, or whatever shape you want. Place the pastry on a baking sheet lined with parchment. Prick with a fork at a couple inch increments to prevent the pastry from forming big bubbles while baking.
Spread the onions over the pastry, all the way to the edges of the pastry. Dot with the cheese, sprinkle with the tarragon. Refrigerate if not baking immediately.
Bake in a preheated oven at 400F for 18 to 20 minutes or until the cheese has melted and the pastry is crispy.
Cool for 5 minutes then cut into wedges or squares and enjoy!