Preheat the oven to 350℉ and grease & flour three 8 inch round pans. We also like to line the pans with circles of parchment paper.
In a medium size bowl whisk together the flour, baking powder and salt. Set aside.
In another bowl combine the egg whites, champagne, vanilla and vegetable oil. Whisk until blended and set aside.
In the bowl of your mixer, mix the butter and sugar on medium speed for 3 to 5 minutes until light and fluffy.
While mixing on low speed, add the flour mixture and egg whites mixture alternately. Start and end with the dry ingredients. We do three additions of dry ingredients and two additions of wet. Mix just until incorporated.
Pour into prepared pans and bake 25 to 30 minutes. The cake is done when a toothpick inserted the center comes out clean. Cool in baking pans 10 min. then turn out.
Cream the softened butter until smooth and lightened in color.
Blend in the salt and vanilla.
Gradually add the powdered sugar with the champagne until the powdered sugar is incorporated. Beat at medium speed 3 to 4 minutes. The texture will become very smooth. If you are tinting the entire batch of buttercream light pink, you can add a very small amount of coloring gel while it is mixing.
