Place softened butter in a large bowl, using either a standing mixer or hand mixer. Beat for 2-3 minutes until it’s light and airy. Gradually add powdered sugar, beginning on low speed to prevent splattering, until it becomes crumbly. Pour in the vanilla, champagne, and salt, blending until smooth. If you prefer, you may add the pink food coloring at this point.

When ready to frost, increase the speed to medium-high, whipping for 3-5 minutes until the frosting is creamy and fluffy. The frosting can be made 1-2 days ahead and kept in an airtight container in the refrigerator. Bring it to room temperature and give it a quick remix before applying to the cake.

Preheat your oven to 350°F. Prepare three 6-inch round cake pans by lining the bottoms with parchment paper and lightly greasing with baking spray, or by coating them with butter and flour. Set these aside.

In a medium mixing bowl, whisk together flour, baking powder, and salt until well combined. In another large bowl, cream the softened butter with sugar, beating for 2-3 minutes until light and fluffy. Blend in the vanilla extract and add egg whites gradually, mixing on low speed to incorporate each addition thoroughly. Scrape down the bowl as needed.

Alternate adding the flour mixture and champagne to the butter mixture, beginning and ending with the dry ingredients. Divide the dry mixture into three parts and the champagne into two, incorporating them in stages. Avoid overmixing to keep the cake tender.

If using pink food coloring, begin adding it after the second addition of flour, giving you control over the color without overworking the batter. Evenly distribute the batter between the three prepared pans, smoothing the tops with a spatula.

Bake for 25-30 minutes, checking for doneness with a toothpick in the center of each cake; it should come out with just a few crumbs attached. Let the cakes cool in their pans for 10 minutes before transferring them to a wire rack to cool completely.

Once fully cooled, assemble and frost your cake, decorating with any optional toppings like a white chocolate drip, chocolate-covered strawberries, or champagne marshmallows. Enjoy your beautifully layered Pink Champagne Cake!