Stir together flour, baking powder, cinnamon, orange peel, baking soda, nutmeg, and salt in a medium bowl; set aside. Beat together eggs, sweet potato, granulated sugar, and oil in a large mixing bowl. Add flour mixture; beat until well combined. Stir in pecans and raisins.
Spread batter in an ungreased 15x10x1-inch baking pan. Bake in a 350 degree F oven for 25 to 30 minutes or until a toothpick inserted in center comes out clean. Cool in pan on a wire rack. For the Cream Cheese Frosting, beat together cream cheese, butter, and vanilla until fluffy. Gradually add powdered sugar, beating until smooth. Frost bars with Cream Cheese Frosting. Cut into squares. Store in refrigerator. Makes 24.