Preheat oven to 350°. Butter a baking pan and spread pear wedges on it in one layer. Bake until tender when pierced with a fork, 25 minutes. Let pears cool, cover with plastic wrap, and chill overnight.
In a large frying pan over medium-high heat, melt 2 tbsp. butter. Add pears, rosemary, and salt. Cook, stirring occasionally, until pears are brown and caramelized, 15 minutes. Stir in pepper and remove rosemary sprig. Serve hot or at room temperature.
Note: Nutritional analysis is per serving.