1Heat oven to 375°F. Spray bottom and sides of 9x5-inch loaf pan with cooking spray.
2In large bowl, mix 2 1/4 cups flour, the granulated sugar, baking powder and salt. In medium bowl, beat buttermilk, 6 tablespoons butter, the vanilla, lemon peel, gingerroot and eggs with wire whisk until well blended. Stir into flour mixture until blended. Stir in pears and hazelnuts. Spread batter in pan.
3In medium bowl, mix brown sugar and 1/4 cup butter until blended. Stir in 2/3 cup flour; pinch with fingers until clumps form. Sprinkle topping over batter.
4Bake 1 hour to 1 hour 5 minutes or until toothpick inserted in center comes out clean, covering with foil during last 25 minutes to prevent overbrowning, if necessary. Cool 10 minutes; remove from pan to cooling rack. Cool completely, about 2 hours. In small bowl, mix powdered sugar and milk until thin enough to drizzle. Drizzle over loaf. Let stand 10 minutes.