Preheat oven to 350 degrees F. Arrange baguette slices on a cookie sheet and toast in the oven until lightly browned, about 7 minutes. Remove from oven. Meanwhile, combine remaining ingredients in a food processor and blend well. Spoon the dip into a serving bowl and arrange the toasted baguette slices on a platter around it. Garnish with the rosemary sprig and extra walnut pieces.