In a large stockpot, heat 2 tablespoons of olive oil over medium heat. Add diced onions, carrots, and celery to the pot, sautéing them for about 3–4 minutes until they turn tender and translucent. Add minced garlic, cooking for an additional minute until fragrant.

Pour in 6 cups of low-sodium chicken broth or vegetable stock, increasing the heat to medium-high. Stir in herbes de Provence, kosher sea salt, black pepper, paprika, and rosemary, followed by yellow split peas and green lentils. Reduce the heat, and let it simmer uncovered for 30 minutes.

After 30 minutes, introduce the diced butternut squash, potatoes, and celery root. Stir well to incorporate, then continue to simmer for another 30 minutes or until all vegetables are fork-tender.

Carefully blend about 4 cups of the soup directly in the pot using an immersion blender, or transfer to a standing blender. Add ¼ cup of olive oil and blend until smooth. Return the mixture to the pot, stirring to combine.

Fold in chopped kale and fresh parsley, simmer for 5–8 minutes, stirring occasionally, until the kale is tender yet retains its color.

Remove the pot from heat and allow the soup to rest for about 5 minutes. Ladle into bowls and serve warm.