This simple yellow cake is made in a 9x13 inch pan, sliced in half, filled and topped with a fluffy marshmallow icing.
Preheat oven to 350 degrees F.
Line a 9x13 inch pan with parchment paper.
Grease with butter and dust the parchment paper with a little flour. Set aside.
Separate the eggs.
Beat the egg whites in a medium size bowl using and electric mixer until they are stiff. Set aside.
In a large mixing bowl, beat the butter until it is creamy smooth. Add the sugar and beat for 2 more minutes.
Add the egg yolks all at one time and beat for another minute until the is fluffy and light in color.
Beat in the vanilla extract.
Place the flour, baking powder, and baking soda in a clean mixing bowl and stir to combine.
In increments, alternately add the flour and the buttermilk to the butter mixture. Mix in to combine, but don't over beat.
Fold in the stiff egg whites using a rubber spatula,then pour into the prepared cake pan.
Place into the preheated oven and bake for 35 minutes or until a toothpick inserted in the center comes out clean.
Remove and place the cake onto a rack to cool.
After 10 minutes remove the cake from the pan onto the cooling rack and peel off the parchment paper.
Once the cake has cooled completely, use a large knife to slice the cake in half so you end up with two thin layers.
In a sauce pan bring to boil some water (about 2 inches deep). Reduce heat to a simmer. In a mixing bowl place water, cream of tartar, sugar, egg whites and light corn syrup.
Place bowl into simmering water and turn off heat. Whip egg whites with an electric mixer for about 3 minutes. With a thermometer check the temp of egg whites they should be at 140F, if the temperature is too low return to water. Continuing whipping to stiff peaks. Fold in vanilla.
Layer the cake with the icing. Sprinkle coconut on top.
*Optional: Serve with a small scoop of vanilla ice cream if desired and garnish with decorator white chocolate garnishes.