Preheat the oven to 325°F (165°C). Grease and flour two 9-inch round cake pans.
In a medium bowl, whisk together the all-purpose flour, cake flour, baking soda, baking powder, and salt.
In a separate large bowl, beat the granulated sugar, vegetable oil, and butter-flavored shortening until light and fluffy.
Add the eggs one at a time, then mix in vanilla extract, lemon extract, and lemon zest.
Gradually add the dry ingredients to the wet ingredients, alternating with buttermilk. Mix until just combined.
Stir in the white vinegar and hot lemon water. If desired, add yellow food coloring.
Divide the batter evenly between the prepared cake pans. Bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean. Let cool completely.
For the frosting, beat the softened cream cheese and butter until smooth. Add vanilla extract, lemon extract, and lemon zest.
Gradually mix in the powdered sugar until smooth. Add lemon juice if needed for consistency. If desired, add yellow food coloring.
Once the cake is cool, frost the top of one layer, place the second layer on top, and spread frosting over the entire cake. Garnish with lemon zest or slices.