Dice the onion, carrots, and garlic. Preheat the oven to 400°F (200°C). Keep the puff pastry, peas, and vegan chicken cold until just before you need them.
Heat a shallow dutch oven to medium-high heat on the stovetop. Pour in the olive oil and allow it to heat up. Add the onions and carrots. Sauté the for 3-5 minutes or until the onions are translucent. Add the garlic and continue to stir for another minute.
Lower the heat to medium-low and stir in the flour till the vegetables are coated. Pour in the plant milk, broth, and seasoning. Stir occasionally as it cooks (and thickens) for about 10-15 minutes.
Once the filling is thick and creamy, stir in the frozen peas and frozen vegan chicken. Let this filling cool for a few minutes while preparing the puff pastry.
Defrost the puff pastry in the microwave according to the package instructions. Cut it into squares or rectangles. *See other ideas below. Smooth the top of the filling and place the pastry squares over it. Slightly overlap each one while leaving some gaps for the steam to escape. Brush the dough with a little bit of plant milk for a golden color.
Bake it for 30-35 minutes or until the pastry is a golden brown. Remove the pot pie from the oven and let it cool for a few minutes. Enjoy!