Preheat the oven to 350º F (180°C). Generously grease and flour two 8- or 9-inch cake pan and line the bottoms with parchment paper.
In a large bowl, sift flour, baking powder, baking soda, and salt. Set aside.
In a large bowl or liquid measuring cup, stir together orange juice, milk, and vanilla extract.
In a large bowl, beat the sugar and butter until creamy and pale at medium-high speed. Scrape down the sides and up the bottom of the bowl with a rubber spatula as needed. Add orange zest and mix until incorporated.
Reduce speed to low and mix half of the flour mixture until just combined. Add wet ingredients mixture in three additions, scraping down the mixing bowl with a spatula, and turn the batter over several times to ensure all ingredients are well incorporated. Add the remaining half of the flour; beat just until combined. Do not overmix the batter.
Evenly divide the batter between the prepared pans. NOTE: The orange cake batter is thick, so use a spatula to spread it into the pan, if necessary.
Bake for 25 – 30 minutes, or until a toothpick inserted in the center comes out clean. Allow cakes to cool on a wire rack for 10 – 15 minutes before removing them from the pans. Allow the cakes to cool completely on the wire rack. The cake must be completely cool before frosting.