1 large yellow onion, chopped 1 pound sweet carrots, sliced 2 cups greens (kale, spinach, collard greens, chard), chopped coarsely 6 tbsp unsalted butter 1/4 tsp cayenne pepper 1/4 tsp ground ginger 1 pinch saffron 1 tbsp maple syrup salt and pepper to taste Melt 4 tbsp butter in large, heavy saucepan over medium-high heat Add salt, pepper, cayenne and ginger; cook about a minute Add onions; saute over medium heat until they start to soften Add greens; saute and stir until well-coated Add carrots; saute 4-5 minutes more Add enough water to cover carrot mixture; bring to simmer Cook until carrots are soft, about 15 minutes Add maple syrup and salt and pepper to taste Working in batches, puree soup in a blender, making sure not to fill blender more than 1/3 full Add saffron to soup; return to saucepan and let steep for a few minutes Adjust seasoning and serve