To prepare the Cake, preheat oven to 350F and grease and flour three 6" cake rounds, line with parchment.
Whisk baking powder, flour, and salt in a medium bowl. Set aside.
Using a stand mixer fitted with the paddle attachment, beat butter until smooth. Add sugar and beat it till it become fluffy (2-3mins).
Reduce speed and add egg and whisk it. Add vanilla.
Alternate adding flour mixture and champagne, beginning and ending with flour (3 additions of flour and 2 of champagne).
Add a small amount of Fuschia color gel using a toothpick. Mix to incorporate
Spread batter evenly into prepared pans.
Smooth the tops with a spatula
Bake for approx. 35 mins or until a toothpick inserted into the center comes out mostly clean.
Place cakes on wire rack to cool for 10mins then turn out onto wire rack to cool completely. The Cake is ready, now moving on to Vanilla Buttercream
Place egg whites and sugar into the bowl of a stand mixer,
Place bowl over a hot water bath on the stove and whisk constantly until the mixture is hot
Place bowl on your stand mixer and whisk
Switch to paddle attachment. Slowly add cubed butter and mix until smooth and add vanilla extract
To assemble the cake, Place one layer of cake on a cake stand or serving plate. Top with approximately 2/3 cup of frosting and spread evenly. Repeat with remaining layers and apply a thin coat of frosting all over the cake. Chill for 20mins.
Frost and smooth the sides. Chill for 20mins.
Using a toothpick, add a small amount of Fuschia color gel to the remaining frosting. Stir with a spatula to incorporate, or place back on the stand mixer to mix in the color.
Gently press cake sparkles or sanding sugar into the sides and top of the cake