Heat oven to 350 degrees.
Grease bottoms and sides of 3 (8-or 9-inch) round pans with shortening; lightly flour.
In medium bowl, mix flour, baking powder, baking soda and salt; set aside.
Place peach slices in blender container.
Cover; blend about 30 seconds or until smooth.
Pour 1 cup pureed peaches into small bowl; stir in peach nectar, 2 teaspoons vanilla and orange peel.
Reserve remaining puree for frosting.2.
In a large bowl, beat 1 cup butter with electric mixer on medium speed 30 seconds.
Gradually add granulated sugar, about ¼ cup at a time, beating well after each addition.
Beat 2 minutes longer.
Add eggs, one at a time, beating well after each addition.
On low speed, alternately add flour mixture, about one-third at a time, and peach mixture, about half at a time, beating just until blended.
Pour 2 cups batter into each pan.3.
Bake 25 to 30 minutes or until toothpick inserted in center comes out clean.
Cool 10 minutes; remove from pans to cooling racks.
Cool completely, about 40 minutes.4.
For filling, in large bowl, beat 1 cup of the butter with electric mixer on medium speed until creamy.
Beat in 4 cups of the powdered sugar on low speed, 1 cup at a time, until smooth.
Beat in 2 tablespoons reserved peach puree and ½ teaspoon vanilla.
Place 1 cake layer on cake plate, top side up.
Spread 2/3 cup frosting over top.
Top with second layer, top side down; spread with 2/3 cup filling.
Top with remaining layer, top side up.
Thinly frost side and top of cake with remaining filling; set aside.5.
In large bowl, beat remaining 2 cups butter with electric mixer on medium speed until creamy.
Beat in remaining 8 cups powdered sugar on low, about 1 cup at a time, until creamy.
Beat in 4 tablespoons peach puree, 1 teaspoon vanilla and food color until desired peach color.6.
Fill decorating bag fitted with large open star tip (½-inch opening).
Starting about 1 ½ inches from bottom edge of cake, make center of rosette flower by squeezing frosting in a tight circle.
Continue making concentric circles around center, to make flower about 3 inches in diameter.
Make flowers to cover side of cake, staggering up and down around cake.
Make flowers on top of cake and fill in open spaces with wavy lines.
Sweet tips: The first layer of frosting for this cake is called a crumb coat.
It coats and sets the crumbs so they don't combine with the outer frosting, making for a much prettier cake.
Got leftover pureed peaches?
Add them to a smoothie for a delicious flavor twist.