Cream the butter on medium speed until it is light and smooth, about 1 to 2 minutes. Add the sugar and continue mixing until it’s well blended, light and fluffy, about 2 minutes.
In a large measuring cup, whisk together the buttermilk, eggs, and vanilla extract.
In a medium mixing bowl, whisk together the flour, baking soda, baking powder, kosher salt, and nutmeg.
Using low speed, add the flour mixture about one cup at a time to the butter and sugar, alternating with the buttermilk. Mixing each addition just until it is blended into the dough.
Divide the dough in half (it’s easier to handle) and turnout onto floured parchment sheets. Gently knead extra flour into dough until it’s no longer sticky to the touch.
Flatten each round of dough into a disc, wrap it in the parchment sheet and seal it up in a plastic bag. The dough is very soft, so you’ll want to chill it at least one hour before you roll it out.
When you’re ready to bake, gently roll out the dough onto a surface dusted with flour. Dust the rolling pin with flour as needed, rolling the dough to a thickness of about ¼” thick. Cut with a cookie or biscuit cutter.
Place the tea cakes on a baking sheet lined with either a Silpat liner or parchment paper. Sprinkle the tops with additional sugar.
Bake the tea cakes at 350-degrees for about 15 minutes, or until they are lightly golden on the bottom. They will still be light in color on top.
Transfer to a wire rack to cool completely.