Karim Arsanios' onion soup in a puff pastry crust

Soup

1. Thinly slice the onions using a mandolin.
2. Heat the olive oil in a pot and add the onions. When they turn translucent, lightly season with salt.
3. Cook over low heat, stirring often, until very soft and caramelized, about 30 minutes.
4. Deglaze with the white wine and let it reduce completely. Allow the onions to caramelize slightly.
5. Deglaze with the Calvados and flambé.
6. Let reduce again, then add the chicken stock, water and thyme.
7. Simmer over low heat until reduced by half, about 30 minutes.

Croutons

1. Cut the bread into small cubes. Chilling it briefly in the freezer helps with slicing. You should have about 20 croutons.
2. In a bowl, toss the bread cubes with olive oil, thyme and crushed garlic.
3. Bake at 160°C (320°F) for about 25 minutes, until dry and very crisp.

Assembly (per ramekin or bowl)

1. Use a ramekin 10 to 11 centimeters wide and 5 to 8 centimeters deep. Fill it three-quarters full with soup.
2. Add a spoonful of onions at the bottom for extra richness.
3. Sprinkle one-quarter of the grated Parmesan-Pecorino mixture over each ramekin, then add 4 to 5 croutons.
4. Roll out the puff pastry very thin, lightly dusting with flour if needed. Cut into four pieces.
5. Stretch one piece of pastry over each ramekin, sealing the edges well.
6. Separate the egg yolk from the white. Lightly brush the pastry with the yolk to help it brown.
7. Sprinkle with fleur de sel and decorate with a sprig of thyme.
8. Bake at 215°C (420°F) for 10 to 15 minutes, depending on the oven, until the pastry is puffed and golden.