Grease and flour 15 X 11 X1 inch sheet pan and set oven to 375 degrees
In a sauce pan, melt the butter and add 1 cup of water and bring to a boil
Remove from heat, set aside and let cool a bit
In a large bowl whisk the flour, sugar, baking soda, cinnamon, and nutmeg until well blended
Add the eggs, vanilla and buttermilk (or sour cream) to the cooled butter mixture and add to the dry ingredients
Fold in the chopped apples (batter will be stiff)
Pour into prepared pan and use a flat spreader to even out the top
Bake for about 22 minutes or until toothpick inserted comes out clean.