Preheat your oven to 350°F (175°C) and grease two 9-inch round cake pans.

In a large bowl, whisk together the flour, sugar, salt, baking soda, and cocoa powder.

In another bowl, combine the buttermilk, vegetable oil, eggs, blue food coloring, and vanilla extract until well blended.

Gradually add the wet ingredients into the dry mixture, and mix until just combined.

Stir in the vinegar very last for a tender, velvety crumb.

Divide the batter evenly between the prepared pans and bake for about 30–35 minutes, or until a toothpick comes out clean.

Let the cakes cool in the pans for 10 minutes, then turn them out onto wire racks to cool completely.

In a bowl, beat the softened cream cheese and butter until creamy.

Gradually add the powdered sugar, mixing until smooth, then stir in the vanilla.

If too thick, add a splash of milk to reach the desired consistency.

Once the cake layers are completely cool, spread a layer of frosting on top of the first cake, stack the second, and frost the top and sides.

Optional: Add sprinkles or blueberries for aesthetic flair.

Slice into your masterpiece and enjoy!