Preheat the oven according to the directions of your cake mix or recipe. Grease the sides and bottoms of two 9" cake pans, and line each pan with a round of parchment paper. 
 

Make the first batch of cake batter (you'll make two). After you add the eggs, add 1 packet of yellow food coloring and blend well. If your batter is vegan, you can complete this step with your liquid ingredients, before adding the flour.) Continue on with the recipe.   
 

When your batter is ready, pour or spoon batter equally between the two prepared cake pans. Bake according to directions, then cool completely. Run a butter knife around the edge of the cake pans, then carefully turn the cakes out onto a cooling rack.
 

Repeat steps one through three, this time adding 1 packet of orange food color.
 

Make the frosting. Place room temperature butter and cream cheese in the bottom of a mixer, and blend on medium speed until fully combined.
 

Turn the mixer off, then add vanilla and confectioners sugar. Place a towel over the mixer, then blend on very low speed until sugar is incorporated. Remove the towel and increase speed to medium high, and beat until fluffy. Add grated lemon peel and briefly blend to incorporate.
 

Assemble the cake.