In a large bowl, sift together the flour, sugar, baking soda, salt, and cocoa powder.
In another large bowl, whisk together the oil, buttermilk, eggs, food coloring, vinegar, and vanilla.
Using a standing mixer, mix the dry ingredients into the wet ingredients until just combined and a smooth batter is formed.
Pour the cake batter evenly into the prepared cake pans.
Place the pan in the oven. Bake, rotating the pans halfway through the cooking, until the cake pulls away from the side of the pans, and a toothpick inserted in the center of the cakes comes out clean, about 30 minutes.
Remove the cake from the oven.
Mix all ingredients (exlcuding mason jars) together and store in fridge before use.
To assemble trifles
Make sure red velvet cake is fully cooled.
Use the lid to the mason jar or a round cookie cutter to make circles out of the red velvet cake. *OR break up the red velvet cake and crumble into jar.
Layer Red Velvet Cake and use a piping bag (or Ziploc bag with a corner cut off) to pipe frosting for three layers and sprinkle with crushed pecans if desired.