Melt 4 Tbs. of the butter in a large stockpot over medium-high heat. Add the zucchini and 1 tsp. salt and cook, stirring occasionally, until the zucchini is crisp-tender but not browned, about 5 minutes. Add the garlic and cook for 1 minute. Using a slotted spoon, transfer the zucchini mixture to a medium bowl.
Melt the remaining 2 Tbs. butter in the stockpot over medium-high heat. Add the onion and cook, stirring, until it becomes translucent, about 3 minutes. Increase the heat to high, add the tomatoes and 1 tsp. salt to the pot, and cook, stirring constantly for 1 minute. Add the chicken broth and the wine and bring to a boil. Reduce the heat and simmer, stirring occasionally, until the liquid has reduced by half, about 20 minutes.
Remove the pot from the heat and let the tomato mixture cool slightly. Purée the soup in the pot with a hand blender or in batches (with the top vented) in a regular blender. If you use a regular blender, return the soup to the pot. Add the cream. Bring to a boil and cook until heated through, about 2 minutes. Stir the zucchini into the soup. Garnish each serving with some of the chopped fresh basil.
Serve with toasted baguette slices smeared with goat cheese.