1. In an electric bowl mixer, beat butter and sugar together until light and fluffy.
2. Add eggs one at a time, beating after each addition, add lemon zest and juice, and mix well.
3. In a separate bowl, whisk together dry ingredients.
4. With the mixer on low, slowly add the dry ingredients into the batter.
5. Carefully fold in the blueberries after all the ingredients have been mixed together.
6. Allow dough to cool in the refrigerator for at least an hour and up to overnight.
7. Preheat oven to 350.
8. Use a small scoop (about 1 tbsp size) and place rounded balls of dough on a cookie sheet lined with parchment paper or foil (or non-stick cookie sheets).
9. Bake for 11-14 minutes, until the bottoms are slightly golden brown (the edges should not brown).