In a Dutch oven, heat butter over medium-high heat; saute onion and garlic until tender, 7-9 minutes. Stir in flour and paprika until blended; cook and stir 2 minutes. Gradually stir in broth. Add chopped pears; bring to a boil. Reduce heat; simmer, covered, until pears are tender, about 15 minutes, stirring occasionally., Puree soup using an immersion blender or cool slightly and puree soup in batches in a blender; return to pan. Add cheese and pepper; cook and stir over low heat until cheese is melted, 3-5 minutes. If desired, top with pear slices.