Preheat the oven: Preheat your oven to 400°F. Take your sheet of puff pastry and place it on a baking sheet. Bake it for approximately 15-20 minutes until golden brown and flaky. Remove from the oven and let cool.
Cook the chicken: In a large pot or Dutch oven, heat 1 tbsp of olive oil over medium heat. Add the 1 lb of cubed boneless, skinless chicken and cook until no longer pink, about 6-8 minutes. Remove the chicken from the pot and set aside.
Sauté the vegetables: In the same pot, add the 1 diced onion, 2 minced garlic cloves, and 2 sliced carrots. Sauté for about 4-5 minutes, or until the onion is translucent. Add 1 diced large potato to the pot and stir for another 3-4 minutes.
Make the soup base: Sprinkle 1/4 cup of flour over the vegetables and stir continuously for about a minute to cook the flour. Gradually whisk in 4 cups of chicken broth until smooth. Bring the mixture to a simmer, then add the cooked chicken back into the pot. Include 1 cup of frozen peas, 1 cup of frozen corn, 1 tsp of dried thyme, salt, and pepper to taste. Let it simmer for about 15-20 minutes until the potatoes are tender.
Add the cream: Stir in 1 cup of heavy cream and continue to simmer for another 5 minutes until the soup thickens slightly. Adjust seasoning as needed.
Serve: Ladle the soup into bowls and top each with a piece of the baked puff pastry. Garnish with fresh parsley and enjoy!