1 sheet puff pastry
4 yellow onions, sliced thin along the grain
Sprig of rosemary
2 anchovy filets, cleaned and sliced diagonally
5 or 6 pitted nicoise olives, sliced
Sprig of thyme
1 egg yolk mixed with a few drops of water
Preheat oven to 425 degrees.
Sauté onions in butter, add rosemary, lightly salt, and cook over medium heat until caramelized.
Add a dash of cassis and cook off. Turn off heat and cool slightly.
Roll out puff pastry to desired shape (square, rectangle, or circle), puncture in places with a sharp knife, put on a sheet pan covered with parchment paper.
Spread cooked onion with a light hand over puff pastry leaving a small rim.
Scatter thyme leaves, sliced anchovy filets, and olive slices over top. Paint rim with egg yolk.
Bake in oven for five minutes, check, and turn pan in oven. Cook till bottom of crust is light brown.
Let cool slightly, cut, and serve with fresh herbs tossed with fleur de sel, lemon, and olive oil.