Preheat oven to 350°F.Grease a 9x13 jelly pan with white vegetable shortening and line with parchment;grease parchment paper.

In a large bowl, beat eggs with a hand mixer for 5 full minutes - set a timer if you need to! Properly whipped eggs will lighten in color considerably and have the appearance of yellow cake batter.

With the mixer still running, slowly add sugar and oil to the whipped eggs. Next, add buttermilk, vinegar, vanilla extract and food coloring (add food coloring a little at a time until desired color is achieved).

Sift together flour, baking powder and salt. Slowly add to the liquid ingredients. Mix until well combined.

Pour batter into prepared pan and tilt pan to distribute batter evenly.

Sprinkle a cotton tea towel with powdered sugar and rub sugar into the towel with your hands. Terry-cloth towels and towels with texture (such as waffle pattern) are NOT ideal for making cake rolls.

Bake for 12-15 minutes. Check at 12 minutes. Cake is done when it springs back when pressed with fingers.

When cake is baked turn it out onto the tea towel - do this without delay! Peel off parchment and immediately roll cake into the tea towel, beginning at the narrow end. Roll tightly and as evenly as possible. Place rolled cake on a wire rack seam-side down and let cool completely.

For the Swiss buttercream filling Whisk egg white(s) and sugar together in a large heat-proof bowl over a pot of simmering water. Whisk constantly until the sugar melts into the egg white. Check consistency by rubbing a bit between two fingers. If sugar granules remain, keep heating/whisking.

When sugar and egg white are blended, transfer to a stand mixer. Whip until the mixtures doubles in size. Add vanilla extract, and then whip in softened butter a little at a time until mixture has thickened to buttercream icing consistency.

Assembly:Carefully unwrap/unroll velvet cake, allowing the most tightly rolled end to curl slightly (see video). Frost inside with Swiss buttercream and roll cake tightly. Cut into pieces with a serrated knife and serve.

Pretty when garnished with sweetened whipped cream and glace' or maraschino cherries.