Preheat the oven to 350°F. Generously grease three 6-inch cake pans, two 8-inch cake pans or 9-inch cake pans. If desired, additionally line the bottom of the cake pans with parchment paper rounds for easy cake removal. Whisk together the flour, baking soda, baking soda, and salt in medium mixing bowl. Set aside.
In a large mixing bowl, whisk together the melted butter, sugar, and yogurt until combined. Then add the eggs, vanilla, orange juice, orange zest and whisk until completely combined. The mixture will be gritty.
Add half the dry ingredients to the wet ingredients, whisking until almost incorporated, then add the remaining dry ingredients. Whisk until the batter is smooth, a few small lumps are OK. The batter will be thick.
Divide and pour the batter evenly into the prepared cake pans. Gently tap the cake pans on the counter. Bake for 35-40 minutes, until springy to the touch and a toothpick inserted into the center of the cake comes out clean or with a few moist crumbs.
Allow the cakes to cool in the pans for 20 minutes, then remove the cakes from the pans and set on a wire rack to cool completely. The cakes must be completely cool before frosting and assembling.
Make the frosting: In a large bowl using a hand-held mixer or stand mixer fitted with the paddle attachment, beat the cream cheese and butter medium-high speed until creamy, about 1 minute. Scrape the bottom and sides of the bowl and beat again for 30 seconds. Turning the mixer to low speed, add the heavy cream, vanilla, and salt. Then, slowly add the powdered sugar– I find it's helpful to use a 1/3 dry measuring cup while adding. Once all the powdered sugar is added, adjust the speed to medium and beat for 1 minute. Scrape down the bottom and sides of the bowl, then beat together for another 30 seconds until creamy. If the frosting is too thick, add 1 teaspoon heavy cream. If too thick, add 1-3 Tablespoons of powdered sugar.
Assemble and frost: Using a large serrated knife or cake leveler, layer off the tops of the cakes to create a flat surface. Place 1 cake layer on your cake stand and evenly cover the top with frosting. Top with 2nd layer, more frosting, and then top with the 3rd layer. Spread remaining frosting all over the top and sides. If desired, decorate the top and sides of the cake with fresh or candied orange slices. Refrigerate cake for 20 minutes before slicing. This helps the cake hold its shape when cutting. Cover the leftover frosted cake tightly and store in the refrigerator for up to 5 days.