In medium bowl, mix flour, baking powder, allspice and salt; set aside. In large bowl, beat butter and granulated sugar with electric mixer on low speed 30 seconds, scraping bowl frequently. Beat on high speed 3 minutes, scraping bowl occasionally, until light and fluffy. Add eggs, one at a time, beating well after each addition. On low speed, alternately add flour mixture, about 1 cup at a time, and milk, about 1/2 cup at a time, beating just until blended after each addition. Fold in pears, walnuts and 3/4 teaspoon of the lemon peel. Pour batter into pan.