1. 1. Preheat and Prep: Preheat your oven to 350°F (175°C). Grease and flour a 9×13 inch baking pan. Alternatively, line it with parchment paper, leaving an overhang on two sides for easy removal. You can also use two 8-inch or 9-inch round cake pans for a layered cake; adjust baking time accordingly.

1. 1. Combine Dry Ingredients: In a large mixing bowl, whisk together the sifted all-purpose flour, granulated sugar, baking powder, baking soda, and salt. Whisking helps to aerate the flour and evenly distribute the leavening agents.

1. 1. Combine Wet Ingredients: In a separate medium bowl, whisk together the room temperature large eggs, vegetable oil, room temperature buttermilk, thawed frozen orange juice concentrate, fresh orange zest, and vanilla extract until well combined.

1. 1. Mix Wet into Dry: Gradually pour the wet ingredients into the dry ingredients. Mix on low speed with an electric mixer (or by hand with a whisk) until just combined. Be careful not to overmix; a few small lumps are okay. Overmixing develops gluten, which can result in a tougher cake.

1. 1. Pour and Spread: Pour the batter into your prepared baking pan(s) and spread it evenly with a spatula.

Baking Your Cake to Golden Perfection:

1. 1. Bake: Place the pan in the preheated oven.

      • • For a 9×13 inch pan: Bake for 30-35 minutes.
      • • For two 8-inch or 9-inch round pans: Bake for 25-30 minutes.

1. 1. Test for Doneness: The cake is done when a wooden skewer or toothpick inserted into the center comes out clean or with a few moist crumbs attached. The top should be golden brown and spring back when lightly touched.

1. 1. Cool Completely: Once baked, remove the cake from the oven and let it cool in the pan on a wire rack for 15-20 minutes. If using round pans, carefully invert them onto a wire rack to cool completely. If using a 9×13 pan, you can let it cool completely in the pan. It’s crucial that the cake is completely cool before frosting, otherwise, the frosting will melt.

Whipping Up the Dreamy Orange Julius Frosting:

1. 1. Beat Butter and Cream Cheese: In a large mixing bowl, using an electric mixer, beat the softened unsalted butter and softened cream cheese together on medium speed until smooth and creamy, about 2-3 minutes. Scrape down the sides of the bowl as needed.

1. 1. Add Flavorings: Add the thawed frozen orange juice concentrate, fresh orange zest, vanilla extract, and a pinch of salt (if using). Beat on low speed until just combined.

1. 1. Gradually Add Powdered Sugar: With the mixer on low, gradually add the sifted powdered sugar, one cup at a time, until the frosting reaches your desired consistency and sweetness. If the frosting becomes too thick, you can add a teaspoon or two of milk or more orange juice concentrate. If it’s too thin, add more powdered sugar.

1. 1. Beat Until Fluffy: Once all the powdered sugar is incorporated, increase the mixer speed to medium-high and beat for another 2-3 minutes until the frosting is light, fluffy, and smooth.

1. 1. Add Color (Optional): If desired, add a few drops of orange food coloring and mix until evenly distributed to achieve a more vibrant orange hue. Start with a tiny amount, as you can always add more.

Assembling and Frosting Your Masterpiece:

1. 1. Ensure Cake is Cool: Double-check that your cake is completely cool to the touch.

1. 1. Frost the Cake:

      • • For a 9×13 Cake: Simply spread the frosting evenly over the top of the cooled cake directly in the pan using an offset spatula or a knife.
      • • For a Layered Cake: If you baked round cakes, place one layer on a serving platter or cake stand. Spread a generous layer of frosting over the top. Carefully place the second layer on top. Frost the top and sides of the entire cake.

1. 1. Garnish (Optional): For an extra touch of elegance, you can garnish your frosted Orange Julius Cake with additional orange zest, thin orange slices, candied orange peel, or a sprinkle of shredded coconut.

1. 1. Chill (Recommended): For the best flavor and texture, and to allow the frosting to set, chill the cake in the refrigerator for at least 30 minutes to an hour before slicing and serving. This also makes for neater slices.