Preheat oven to 400 degrees. Peel and cut carrots and onions into large pieces. Peel garlic cloves. Toss carrots, onions, and garlic with olive oil, salt, and pepper. Arrange in a single layer on a baking sheet or roasting pan. Roast in oven until veggies are soft and slightly blackened, about 45-55 minutes.

While veggies are roasting, arrange cashews in a single layer on a second baking sheet. Roast in oven until slightly toasted, about 5-8 minutes. Allow cashews to completely cool.

Optional: Make dried rubbed sage from fresh sage. Arrange 3 fresh sage leaves in a single layer on a microwave safe plate. Microwave until leaves are dried, about 1 minute 30 seconds, moving leaves around every 15-20 seconds. Place leaves in a metal colander and rub leaves against bottom of colander with fingers. The sage that falls through the colander is the dried rubbed sage! Store any extra in an airtight container.

Once veggies are done roasting, combine veggies and stock (except ¼ cup) in a large stock pot. Deglaze pan by pouring remaining ¼ cup stock into roasting pan and scraping all the yummy caramelized veggie pieces off of the bottom of the pan. Add to veggies and stock. Simmer until carrots are tender, about 15-20 minutes.

Once carrots are tender blend soup in batches in a blender (remembering not to fill blender more than half way) or with an immersion blender. In a food processor or good blender grind cashews with ½ cup of soup until it forms a smooth cashew butter. Add back to soup and blend more if necessary. Add thyme, rubbed sage, salt, and pepper to taste.