In a small bowl, mix together the sumac, sesame seeds, thyme, and salt. You'll use 1½ tablespoons of this za'atar in the soup and reserve the rest for garnish. Set aside.
In a large sauce pan, heat 1 tablespoon olive oil over medium heat until it begins to shimmer. Add the onion and garlic and cook, stirring until it begins to soften, but does not yet brown, about 5 minutes.
Add the remaining 2 tablespoons olive oil, carrots, and 1½ tablespoon of the mixed za'atar seasoning. Cook, stirring, for 6-8 minutes, until the carrots begin to soften.
Stir in the maple syrup then add the broth, water, cannellini beans, and salt. Bring to a boil over medium-high heat then reduce heat until the soup simmers. Simmer until the carrots tender when pierced with a fork, 25-30 minutes.
Puree the soup until completely smooth either with an immersion blender or working in batches with a blender or food processor. Return the soup to the pot and stir in the lemon juice and ghee. Taste and adjust seasoning to your liking.
Serve warm topped a swirl of lemon yogurt, cinnamon toasted hazelnuts, a sprinkling of the remaining za'atar, and fresh thyme.
