Step 1

Heat 2 tablespoons of the butter in a large pot or Dutch oven over medium heat.

Step 2

Sauté the leeks and the garlic in the butter until the leeks are tender, about 4-6 minutes.

Step 3

Stir in the sweet potatoes, 3/4 teaspoon of the salt, the cinnamon, the cayenne, and the vegetable stock.

Step 4

Bring the mixture to a boil.

Step 5

Reduce the heat and simmer, covered, until the potatoes are tender, about 15-20 minutes.

Step 6

Use an immersion blender to puree the soup.

Step 7

Stir in the heavy cream and 2 teaspoons of the thyme.

Step 8

Bring the soup back to a boil.

Step 9

Reduce the heat and simmer, uncovered, for 5 minutes.

Step 10

In a large skillet, melt the remaining butter over medium heat.

Step 11

Add the crab, the remaining salt, and the remaining thyme.

Step 12

Stir and cook the crab until heated through, about 5 minutes.

Step 13

Serve the soup topped with the crab mixture and the croutons.