Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

Unroll the thawed puff pastry sheet on a clean surface. Use a 3-inch biscuit cutter or cookie cutter to stamp out 6 rounds. Transfer to the prepared baking sheet, brush lightly with egg wash, and sprinkle with flaky sea salt. Bake for 14-16 minutes until puffed and deep golden brown.

Melt the unsalted butter in a 5-quart Dutch oven over medium heat. Add the diced onion, carrots, and celery. Cook for 7-8 minutes until tender and fragrant.

Stir in the minced garlic, chopped fresh thyme, and rosemary. Cook for 1 minute until highly aromatic.

Sprinkle the flour over the vegetables and stir constantly for 2 minutes to cook off raw starch.

Gradually pour in the chicken broth while whisking continuously. Bring to a simmer over medium heat and let cook for 10 minutes until the broth thickens into a silky velouté.

Reduce heat to medium-low. Fold in the shredded chicken, frozen sweet peas, and heavy cream. Simmer for 4-5 minutes until heated through. Season with kosher salt and black pepper to taste.

Ladle the hot creamy soup into bowls and top each serving with a warm, flaky puff pastry round. Garnish with extra fresh thyme and serve immediately.