Start by chopping your vegetables and prepare all of your ingredients.
Heat the vegan butter in a medium saucepan over medium heat. Add your onion and garlic and sauté for 5 minutes or until fragrant.
Stir in your sliced mushrooms and sauté for another 5 minutes. Add your salt and thyme and cook for another 1-2 minutes.
Add your cashews and broth. Bring to a boil, then reduce heat and simmer over low-medium heat for 15 minutes, covered. Stir occasionally.
Once the soup is done cooking, carefully transfer it to a high-speed blender. Blend until smooth, about 30 seconds. If your blender is too small, work in batches.
Serve immediately or let it cool down and store it in an airtight container in the fridge for up to 4 days. You can also store it in the freezer.