In a bowl of a standing mixer, place the butter and sugar and beat to incorporate, about 1 -2 minutes. Scrape the sides and bottom of the bowl to make sure you have a cohesive mixture.
Add the egg yolk followed by the eggs and mix to incorporate.
Add the orange juice and vanilla extract.
In a small bowl mix, the brandy and baking soda then add it to the butter mixture
Add the baking powder to the flour and mix, With the mixer on low, add 9 cups of the flour. Once the flour has been incorporated, stop the mixer and place the dough on a clean work surface.
Bring the dough into a large ball. If you feel that the dough is too sticky sprinkle the remaining of the flour (up to 1 cup). The dough should be smooth and easy to work with.
Preheat oven to 350F and line 5 cookie pans with parchment paper (if you have less that's ok)
Pinch a small dough ball, about 20 g (About half the size of a golf ball). Roll the dough into a 3" log, then shape it. You can see the traditional Greek shapes ontop.
Place the cookie on a lined pan and keep going until the pan is full. Make sure to leave about 1.5" space between each cookie.
once the pan is full, brush it with the leftover egg whites and bake for 20-25 minutes or just until the cookies are golden ontop and a bit darker at the bottom.
Remove from the oven and allow to cool.