Preheat the oven to 350 degrees F. Line one large or two regular baking sheets with parchment paper.
In a medium-sized bowl, whisk together the flour, zest, baking soda and salt.
In a stand mixer with the paddle attachment, cream the butter and sugar together until light and fluffy, about 3 minutes on medium high speed. Add the vanilla and mix for another 15 seconds to combine.
Turn the mixer speed to low and add the eggs, one at a time, allowing the first to fully incorporate before adding the next. Scrape down the side of the bowl all the way to the bottom after the second egg. With the mixer on medium speed, alternate between adding the flour mixture and buttermilk, until all of the ingredients are incorporated, starting and ending with the dry.
Using a spatula, stir in the blueberries.
Use a 2-tablespoon scoop to portion the cookie dough onto a parchment-lined sheet pan. Space the cookies at least 1 1/2 inches apart (you may need to cook them in batches). Allow to chill for 15 minutes.
Bake for 15 minutes, or until the edges are just starting to brown. Transfer the cookies to a cooling rack after a few minutes.
Store cookies in an airtight container in the refrigerator for up to 2 weeks (possibly longer, but they'll taste best within 2 weeks).