Preheat the oven to 425F

Heat the oil in a large stockpot over medium-high heat

Add the onion, celery, sweet potato, carrot, and thyme

Cook, stirring occasionally, for about 8-10 minutes, until the sweet potato softens

Stir in the flour to coat the vegetables

Add the chicken broth and milk and bring to a boil, stirring constantly, for one minute

Remove from the heat and stir in the chicken and salt, letting it cool for about 20 minutes

Meanwhile, roll out the puff pastry until it has doubled in size

Cut the puff pastry into rounds to fit the top of your ramekins

Place ramekins on a baking sheet and fill with the chicken mixture

Top each with one of the puff pastry rounds

Bake for about 15-18 minutes, until the puff pastry is golden brown

Garnish with thyme