Whisk first five ingredients together in a medium pot. Place over medium heat and bring to a simmer, stirring occasionally. Add cream, stir, and reduce heat to low. Cover and simmer for two to three minutes or until heated through. For the crostini, slice eight half-inch portions from the baguette and toast until crisp. Meanwhile, mix the goat cheese and sage together. Generously spread cheese over each crostini and serve on top of or alongside each soup serving.