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 two bowls.... add red gel food coloring to one.... add green gel food coloring to the second. Stir well.
Spray the bundt pan with Pam spray.
Begin by spooning in some of the red batter and spoon some green on top. Alternate the red and green batter into the bundt pan.
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.