Preheat the oven to 400 degrees(F).
Put the mushrooms and potatoes on a large sheet pan. Drizzle with the olive oil and sprinkle with the thyme leaves and a few pinches of salt and pepper. Toss to coat evenly.
Roast the vegetables for 10 minutes, toss and roast for about 10 to 12 more minutes or until the potatoes are tender.
In the meantime, start the chowder. First, make a cashew cream. Drain the cashews you soaked and add them to a blender. Add 1 cup of non-dairy milk to the blender and a pinch of salt and pepper as well.
Blend on high, scraping down the sides as needed, until the cream is completely smooth. Set aside.
Then, heat the vegan butter on medium high in a large soup pot.
Add the onions, carrots and garlic to the pot. Sauté, reducing heat as needed, until the onion is translucent, about 2 to 3 minutes.
Add the crumbled vegan sausage to the pot, if you are using sausages that have a casing, make sure to remove them.
Break the sausages up into small chunks with a wooden spoon. Continue sautéing, until the sausage is brown and cooked through. About 5 to 6 minutes.
Season with a pinch of salt and pepper. Then add 1 teaspoon of lemon juice to the pot, stir and scrape off any bits of sausage that are stuck to the bottom of the pot.
Then add the vegetable broth, the remaining 1 cup of non-dairy milk, the cashews cream you made, the remaining 1 teaspoon of lemon juice, the sprigs of thyme and a pinch of salt and pepper.
Stir to combine everything and let the chowder simmer for about 15 minutes.
Remove the sprigs of thyme and discard.
Add the vegan cream cheese and stir until it melts into the chowder.
Once the mushrooms and potatoes are done, scoop them into the chowder and stir to combine.
Now, taste and adjust seasonings, adding more salt, pepper or lemon juice if needed.
Serve immediately with crusty bread if desired.