Place the butter, granulated sugar, brown sugar, egg, lemon zest, and lemon juice in the bowl of an electric mixer. Beat on medium high speed with a paddle attachment until well combined. Be sure to scrape down the sides with a rubber spatula if needed. You're looking for a creamy, fluffy texture. Expect to spend around 3-4 minutes mixing.

To the mixing bowl add dry ingredients which include flour, corn starch, and baking soda. Beat on low speed for about 1-2 minutes until there are no more white flour streaks. Do not over-beat. Scrape down the sides of the bowl again if needed.

Remove the bowl from the electric mixer and fold the blueberries into the batter using a wooden spoon or spatula until well combined and evenly dispersed.

Using your hands or a large cookie scoop, measure about 1/4 cup of dough and roll into balls then flatten slightly. You should have around 12 dough balls. Place the cookie dough balls on a large plate and cover with plastic wrap. Refrigerate for 2-3 hours. This step is extremely important.

When you're ready to bake the cookies, preheat the oven to 350 degrees.

Once the oven is preheated, remove the plate from the refrigerator and place the cold cookie dough balls on a parchment paper lined cookie sheet leaving 2 inches apart from each cookie. About 8 cookies will fit on one cookie sheet. It's important to bake the dough balls in their chilled state which is why we don't remove from the refrigerator until the oven is prepped.

Bake cookies for 10-12 minutes or until the middle and edges of the cookies are set. Expect the cookies to firm up a bit once they've cooled. Don't overbake or you risk losing the soft chewy texture.

Place the cookie sheet on a cooling rack to let cool for around 10 minutes. Serve warm immediately or allow to cool to room temperature and store for later.