Preheat oven to 325°F (160°C) and prepare two 9-inch round cake pans with nonstick spray and parchment paper.

Whisk together all-purpose flour, cake flour, cocoa powder, baking soda, and salt in a bowl.

In a separate bowl, whisk buttermilk, red food coloring, vinegar, and vanilla extract.

In a stand mixer, cream together brown sugar and butter until light and fluffy.

Scrape down the sides of the bowl.

Add eggs one at a time, mixing well after each addition.

Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk mixture, beginning and ending with the dry ingredients.

Scrape down the sides of the bowl between additions.

Mix until smooth.

Divide batter evenly between prepared pans.

Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.

Cool in pans for 10 minutes before inverting onto a wire rack to cool completely.

For the frosting, combine cream cheese and butter in a mixer until smooth.

Scrape down the sides of the bowl.

Add vanilla extract and salt.

Gradually add powdered sugar, mixing until smooth.

Refrigerate frosting for 5-10 minutes before using.

Frost the cooled cake and serve.