Melt butter in a large Dutch oven; add onion and next 3 ingredients, and sauté over medium heat 3 minutes. Add sweet potato cubes and chicken broth; cook over medium heat, stirring occasionally, 30 minutes.
Process mixture, in batches, in a blender or food processor until smooth.
Return mixture to Dutch oven; whisk in half-and-half and creamy peanut butter. Reduce heat to low, and simmer, stirring often, 15 minutes. Serve with Nutmeg-Molasses Cream and chopped toasted peanuts.