Using a hand or stand mixer, cream the butter until soft and pale yellow in color.
Gradually add the sugar to the butter, beating well.
Next, add the eggs one at a time, beating well after each addition.
Add the buttermilk and beat well again.
In a medium bowl, combine the flour and soda.
Turn the mixer down to the slowest speed and gradually add the flour and soda mixture into the creamed mixture.
Add in the vanilla.
Shape the dough into a round or rectangle, cover with plastic wrap, and chill several hours or overnight.
Preheat oven to 400 degrees. Lightly grease two cookie sheets.
If you chill your dough overnight, remove it from the fridge about 15 minutes before rolling.
Working with ¼ to ⅓ of the dough at a time, roll dough to ¼” thickness on a lightly floured surface.
Cut the dough into rounds using a large biscuit cutter or a drinking glass dipped into flour. Gather the scraps together, re-roll, and cut until all dough is used.
Place the rounds 1 inch apart on lightly greased cookie sheets.
Sprinkle lightly with additional sugar.
Bake for 7-9 minutes or until the edges are very lightly browned.
Remove the cookie sheets from the oven and allow tea cakes to cool for several minutes before transferring to wire racks to cool completely.