Begin by peeling and chopping the carrots and parsnips into bite-sized pieces; set aside.
Dice the onion finely and mince the garlic cloves, preparing for the flavor base.
Heat a tablespoon of olive oil in the slow cooker on the sauté setting or in a pan over medium heat if preferred, then add the onion and garlic. Sauté until fragrant and translucent—about 3-4 minutes, with a gentle sizzle and a start of golden edges.
Add the chopped carrots and parsnips to the slow cooker, stirring to coat them with the fragrant onion and garlic mixture.
Pour in the vegetable broth, ensuring all the vegetables are submerged. Sprinkle in the thyme and season with salt and pepper to taste.
Cover the slow cooker with its lid, set to low, and cook for about 6 hours until the vegetables are tender and the broth has developed a rich aroma.
Once cooking is complete, stir in the chopped kale, allowing it to wilt into the hot soup for about 5 minutes; the greens should turn bright green and tender.
Taste the soup and adjust the seasoning with more salt and pepper if needed, stirring to blend the flavors.
Serve the soup hot, ladled into bowls, with a sprinkle of fresh herbs or a drizzle of olive oil if desired for an inviting presentation.
Enjoy your hearty, velvety harvest vegetable soup, perfect for a cozy autumn meal.
