Preheat oven to 350°F Line twenty four 2 1/2-inch muffin cups with paper bake cups. Set aside.
In medium bowl stir together flour, baking powder, cinnamon, baking soda, and salt; set aside.
In large mixing bowl beat butter with electric mixer on medium to high speed for 30 seconds. Add sugar and beat on high speed until light and fluffy, about 2 minutes. Add eggs, one at a time, beating on low speed after each addition until combined. Add sweet potatoes and vanilla, beating until combined (batter will be thick).
Divide batter evenly among prepared muffin cups. Bake about 20 minutes or until tops spring back when lightly touched. Cool in pan on wire rack for 1 minute. Remove from pan a cool completely.
Place Cream Cheese Frosting in large resealable plastic bag. Cut a 1/4-inch opening in one corner of bag. Pipe frosting on top of cupcakes. Sprinkle with orange peel.
CREAM CHEESE FROSTING: In large mixing bowl beat one 8-ounce package cream cheese, softened, and 2/3 cup butter, softened, with electric mixer on medium speed for 30 seconds. Add 2 tablespoons bourbon or milk and beat until combined. Beat in 8 cups powdered sugar, about 1/2 cup at a time, until smooth and of good piping consistency. (Makes 4 1/3 cups).