Preheat the oven to 425°F (220°C). In a skillet, heat 1 tablespoon of olive oil over medium-high heat. Sear the chicken breast on each side until browned but not cooked through. Remove from the pan.
Add the remaining tablespoon of olive oil to the pan and toss in the chopped potatoes. Cook for a few minutes until the potatoes begin to brown slightly.
Add the frozen veggie mix and herbs to the pan. Stir and cook until the veggies thaw and soften.
Pour in the chicken broth and bring it to a boil. Then add the cream of mushroom soup and stir to combine. Bring it back to a bubble.
Chop the seared chicken into pieces (it will be raw in the center) and add it to the filling mixture.
Grease 2 ramekins and press 1/4 of the puff pastry sheet into each one.
Use a ladle to scoop 1 cup of the filling into each ramekin. Top each ramekin with another 1/4 of the puff pastry sheet, pressing the edges together.
Brush the egg wash (1 tablespoon water + 1 whisked egg) across the tops of the puff pastry. Make small slits in the top to allow the pie to breathe while cooking.
Place the ramekins into the preheated oven and bake for 12-15 minutes, or until the puff pastry is golden brown on top.
Remove the ramekins from the oven and let them cool on a cooling rack for at least 10 minutes before serving. Remember, the insides will be piping hot, so exercise caution. Serve once cooled to be warm to the touch on the exterior of the ramekin. Enjoy!