Heat a large pot over medium-high heat. Melt the vegan butter into it, then add the onions and carrots. Sauté them for 3-4 minutes or until the onions become translucent. Add the garlic to the pot and stir as it cooks for 1 minute.
Lower the heat to medium, then stir in the flour to coat the vegetables. Mix the cornstarch into the plant-based milk until smooth. Add this to the pot along with the broth, seasoning, rosemary, and potatoes.
Stir occasionally as it cooks (uncovered) for 15-20 minutes or until the potatoes are fork-tender. The soup will become thick and creamy during this time.
Break or chop the frozen vegan chicken into bite-sized pieces and add them to the soup along with the peas. Cook this for 4-5 more minutes until they are heated through.
Enjoy the soup with a baguette, biscuits, crackers, bread, or anything that will help you scoop up every last delicious drop!