Preheat oven to 350°F/180°C.

Grease a cake pan and line the bottom of the pan with a piece of parchment paper.

In a medium bowl, sift together flour,cocoa powder, baking soda, and salt. Set aside.

In a standing mixer fitted with the paddle attachment, beat together butter and sugar on medium speed until light and fluffy, 3-4 minutes.
Scrape down the sides and bottom of the bowl as necessary.
Beat in oil.

Beat eggs, one at a time.

Add vanilla and vinegar and beat until combined. Add red food coloring, until desired colour is reached. With the mixer on low speed, add half of the dry ingredients and beat just until combined.

Add buttermilk, followed by the rest of the dry ingredients. Do not over mix.

Pour the batter in greased pans and sprinkle chopped walnuts. Bake for 30-35 minutes or until a toothpick inserted into the center comes out clean.

Allow cakes to cool in the pan on a wire rack until they're easy to handle, then remove from pan and allow to cool completely on a wire rack.

Enjoy!