• Preheat the oven to 350. Butter three 8” cake pans, top with parchment circles and butter then flour. Set aside.
• In a small bowl, sift together flour, baking powder and salt.
• In the bowl of a stand mixer fitted with paddle attachment, cream the butter and sugar until light and fluffy. Add the egg whites one at a time until well blended. Add in the vanilla extract.
• Alternate adding the dry ingredients and the champagne in three additions, starting and ending with the dry ingredients, mixing until just blended.
• Divide the batter between the cake pans. Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean or they cakes bounce back when lightly pressed. Let cool in pans for 5 minutes then invert and remove from pans to cool to warm
• When cooled but still slightly warm, lightly piece the tops of the layers all over with a fork. Using a pastry brush, brush one tablespoon of the creme de cassis over the tops of the cakes and one tablespoon of the simple syrup over each. Wrap in plastic wrap, place in resealable baggies and freeze 4 hours up to over night.

To frost and fill.

• Make the buttercream. Take out 1 ¼ c and mix the 3 tablespoon of currant jam with it to make the filling. Place one layer on a cake stand or decorating stand and spread ½ of the filling over the top, leaving ½ inch of the edge clear. Top with another layer and repeat with the remaining currant jam filling. Top with the third later and lightly frost the top and sides with the vanilla frosting for the crumb coat. Chill until set then frost with remaining buttercream. Press sparkling sugar into the sides.
• Serve at room temperature