1. Preheat oven to 375 degrees. Toss cauliflower florets with 2 tablespoons olive oil and season with salt and pepper. Place in single layer on baking sheet lined with parchment paper. Roast for 20-25 minutes until tender and lightly browned.
2. Heat remaining oil in large saucepan. Add onion, celery and garlic. Sauté 2-3 minutes until fragrant. Add 4 cups chicken broth, cashews, thyme, roasted cauliflower and potatoes. Bring to a boil, then reduce heat to medium-low and cook 20-25 minutes until potatoes are tender. Add more chicken broth to cover vegetables as needed.
3. Place vegetables and soup in blender and blend until smooth. You may need to do this in two batches.
4. Finely mince turkey bacon. Place in cold skillet and turn heat to medium. Cook, stirring often, until bacon bits are browned and crisp. Transfer to paper towel lined plate.
1. Ladle pureed soup into serving bowls. Top with turkey bacon bits, shredded cheese, chopped scallion and Greek yogurt.