Step 1

FOR THE SALT-AND-PEPPER PUFF PASTRY CROUTONS: Adjust oven rack to middle position and heat oven to 425 degrees. Line rimmed baking sheet with parchment paper. Place puff pastry on lightly floured surface and roll gently to smooth. In small bowl, beat egg with water. Brush pastry with egg wash and then sprinkle evenly with salt and pepper. Using floured cutter, cut puff pastry sheet into small shapes. Transfer pastry pieces to prepared sheet and bake until puffed and golden brown, 10 to 15 minutes, rotating sheet halfway through baking. Set aside.

Step 2

FOR THE CREAMY POACHED CHICKEN: Melt butter in medium saucepan over medium-high heat. Whisk in flour and cook for 1 minute. Slowly whisk in milk, salt, and pepper until smooth. Bring mixture to boil, reduce heat to medium, and cook, whisking occasionally, until thickened to consistency of heavy cream, 5 to 7 minutes. Add chicken and cook, stirring occasionally, until chicken registers 175 degrees, 10 to 15 minutes. Stir in Gruyère and Parmesan and cook until fully melted, 1 to 2 minutes. Remove pan from heat, cover, and set aside.

Step 3

FOR THE SOUP: Heat oil and butter in large Dutch oven over medium heat. Once butter has melted, add potatoes, carrots, leek, fennel, thyme, salt, and pepper. Cover and cook, stirring occasionally, until vegetables are tender, about 15 minutes. Stir in garlic, lemon zest, and wine and cook, uncovered, until fragrant, about 1 minute. Stir in peas, corn, parsley, dill, and poached chicken mixture. Cook until soup is heated through (do not boil), 3 to 5 minutes. If needed, add ¼ cup to ½ cup of water to adjust consistency of soup. Serve topped with croutons.