-Preheat oven to 350 degrees. Prep bundt cake pan.
-Sift flour, baking powder, salt, and baking soda together in a bowl.
-Beat butter on high for 30 seconds.
-Add sugar and vanilla extract to the butter until well combined.
-Add egg whites, one at a time, mixing after each.
-Add eggs, one at a time, mixing after each.
-Add 1/3 C flour mixture to the wet mixture followed by adding 1/3 C of the buttermilk; add 1/3 C flour mixture again then add 1/3 C buttermilk mix on low speed, add 1/3 C of flour and add the rest of 1/3 C of buttermilk mix in low speed until thoroughly blended.
-Divide the batter into three bowls.... add black gel food coloring to one.... add neon orange gel food coloring to the second and add the neon purple gel food coloring to the third bowl. Stir well.
-Spray the bundt pan with Pam spray.
-Begin by spooning in some of the black batter then the neon green next the neon orange and black on top.
-Bake the cake at 350 degrees for 30-35 minutes or until an inserted toothpick comes out clean.
-Allow the cake to cool in the pan for about 20 minutes then remove the cake from the Bundt pan and place on a wire rack until completely cooled.
-Cream the butter and powder sugar until it looks light and creamy.
-If it doesn't cream add several drops of the heavy whipping cream until it creams. Once the frosting has the right consistency then divide it into 3 bowls.
-In each of the three bowls add several drops of gel food coloring. 1 st bowl add black, 2nd bowl add neon purple, 3rd bowl add neon orange. After each color addition stir well to mix the colors.
-When the colors are right, starting with the black frosting using a spoon drizzle the frosting on the cake. Allow the black frosting to dry. Then repeat the process with the neon purple frosting. Lastly, repeat the frosting process with the neon orange frosting.
-Allow all frosting to dry on the cake.