In large bowl, cream together the softened butter, white sugar and brown sugar until combined with a whisk or electric mixer.
Add one egg and vanilla extract and whisk well to combine.
In a separate bowl, combine the flour, baking soda, baking powder, salt, and nutmeg and stir well.
Gradually add the flour, a third at a time, stirring well with a spatual with each addition.
Add the buttermik and stir well to incorporate. Sccop the batter out of the bowl, place on a piece of parchment paper or plastic wrap at least 13 x 9 inches in size. Roll up into a cyclinder shape and press the sides to flatten.
Refrigerate until dough is firm, at least an hour or up to overnight.
Remove the parchment or plastic wrap from the dough and slice into half-inch slices.
Pre-heat oven to 350 degrees and bake for 8 to 12 minutes or until cookies have expanded and are lightly browned on the bottm. Test by carefully using a spatula to look at the bottom of a cookie.
Cool on baking sheet for 5 minutes and then transfer to a wire rack to cool for another 15 minutes.
Serve and enjoy. Store leftovers in an airtight container for up to 3 days. Or freeze them in a freezer safe container or zipper bag.