• Preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.
• Using a hand or stand mixer, beat the eggs on high speed for 5 minutes. Set aside.
• In a large bowl, cream the butter until smooth. Gradually add the sugar and orange peel, beating until light and fluffy.
• Add the beaten eggs and beat for 2 minutes to combine.
• In a separate bowl, mix together the flour, baking powder, baking soda and salt.
• Add the dry ingredients to the wet mixture alternately with the orange juice, beginning and ending with the flour. Beat until smooth.
• Divide batter between prepared pans and bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean.
• Let cakes cool in pans for 10 minutes, then turn out onto wire racks to cool completely.

Orange Buttercream Frosting

• In a large bowl, beat the butter until smooth. Add 3 cups of the sugar, the orange juice, and zest. Begin beating on low until sugar is absorbed.
• Beat until smooth and creamy. Gradually add the remaining 1 cup of sugar. Beat, scraping sides of bowl, until light and fluffy. then continue adding more sugar to taste.
• Optional: Add a drop or two of food coloring for a deeper orange hue.
• Use immediately or store at room temperature for up to 2 days.