Step 1

Preheat the oven to 350 degrees. Line a sheet pan with parchment paper. Lightly dust a cutting board and rolling pin with all-purpose flour. Unfold the sheet of puff pastry on the board, dust it lightly with all-purpose flour, and lightly roll the pastry just to smooth out the folds. With a star-shaped or fluted round cookie cutters, cut 12 stars or rounds of pastry and place them on the prepared sheet pan. Brush the tops with the egg wash, sprinkle with salt and pepper, and refrigerate until ready to bake.

Step 2

Place the chicken on a sheet pan skin side up, rub the skin with olive oil, and season generously with salt and pepper. Roast for 30 to 35 minutes, until a thermometer registers 130 to 140 degrees. Set aside until cool enough to handle, about 15 minutes. Remove and discard the skin and bones and cut the chicken in 1-inch dice. Increase oven temperature to 400 degrees.

Step 3

Meanwhile, melt the butter in a medium (11 to 12-inch) heavy-bottomed pot or Dutch oven, such as Le Creuset, over medium heat. Add the leeks, fennel, and carrots, and sauté over medium-high heat for 10 to 15 minutes, stirring occasionally, until the leeks are tender but not browned.

Step 4

Stir in the garlic and tarragon and cook, stirring often, for 1 minute. Sprinkle on the Wondra flour and cook, stirring constantly, for 2 minutes. Add 1/2 cup of the sherry, the chicken stock, 4 teaspoons salt, 1 1/2 teaspoons pepper, and the Parmesan rind. Bring to a boil over medium-high, lower the heat to low, and simmer, partially covered, for 20 minutes.

Step 5

While the soup simmers, bake the puff pastry croutons for 8 to 10 minutes, until puffed and golden brown.

Step 6

After the soup has simmered for 20 minutes, add the chicken, peas, and onions. Return to a simmer over medium. Simmer uncovered for 5 minutes more. Off the heat, remove the Parmesan rind and add the remaining 1/4 cup of sherry and the parsley. Serve hot in large shallow bowls with two puff pastry croutons on top of each bowl.