In a mixing bowl stir together flour, the 1/2 cup brown sugar, baking powder, cinnamon, ginger, and salt. Make a well in center of flour mixture. In a bowl beat egg; stir in oil, yogurt, and vanilla. Add all at once to flour mixture; stir just till moistened. Stir in pear.
Lightly grease twelve muffin cups or line with paper bake cups; fill two-thirds full. For topping, combine walnuts and the 2 tablespoons brown sugar; sprinkle onto batter in cups. Bake in a 400 degree F. oven about 20 minutes or till golden. Serve warm.