Poppy seed—instead of the sesame seed—makes a great cake garnish, too.
Save time when you choose Betty Crocker® Rich & Creamy ready-to-spread frostings instead of making the Creamy Peanut Butter Frosting. Tint vanilla frosting with orange and yellow food color to make a light tan color for the burger bun layers. Use chocolate frosting for the burger.
Heat oven to 300. Grease 1 1/2-quart round casserole with shortening; lightly flour.
In medium bowl, beat cake mix, water and eggs with electric mixer on low speed 30 seconds; beat on medium speed 3 minutes. Pour into casserole.
Bake 1 hour 5 minutes to 1 hour 10 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes; remove cake from casserole and place rounded side up on cooling rack. Cool completely, about 1 hour.
Cut cake horizontally into 3 equal layers. Freeze pieces uncovered about 1 hour for easier frosting if desired.
In medium bowl, mix powdered sugar and peanut butter with spoon or electric mixer on low speed. Stir 1/4 cup milk. Beat until smooth and spreadable. If necessary, stir in additional milk, 1/2 teaspoon at a tim
Place bottom cake layer on serving plate. Frost side only of layer. Mix 3/4 cup of the remaining frosting and the cocoa; if necessary, stir in 1 to 3 teaspoons milk until spreadable. Frost top of bottom layer with part of the cocoa frosting. Place middle (hamburger) layer on top; frost top and side of middle layer with remaining cocoa frosting.
Drizzle side of middle layer with preserves to look like ketchup. Place remaining (rounded) layer on top. Frost with remaining frosting. Immediately sprinkle top of cake with sesame seed.