Heat oven to 375 degrees. Lay cubed butternut squash in a single layer, roast for 30-35 minutes or until squash is fork tender.
While butternut squash roasts, place sliced mushrooms and rosemary leaves in a medium skillet over medium heat. Turning occasionally, the mushrooms will release enough liquid to prevent sticking. Saute until they have reduced in size by half and browned. Remove from heat and set aside.
Remove from oven and transfer to a large food processor or large dutch oven. using the food processor or a stick/immersion blender, blend butternut squash with apple butter through fine sea salt.
If you are serving your soup chilled, place in the refrigerator until fully cooled. If you are serving soup warm, heat over medium heat on large Dutch oven or pot.
To serve, ladle into soup bowls. Top with 2 tablespoons mushrooms and 4 pieces of jumbo lump crab per bowl.
Enjoy your Butternut Squash Soup with Jumbo Lump Crab and Rosemary Mushrooms!