Preheat oven to 350 degrees
In a large bowl, whisk together brown and white sugars until well-combined. Cream in the butter on low speed until fluffy.
Mix in your vanilla extract, egg and lemon juice.
In a medium bowl, whisk together the flour, salt, baking soda, baking powder, and cornstarch. Add the dry ingredients into the bowl with the wet ingredients.
Mix on medium speed until fully combined. Make sure not to over-mix.
Roll 2 tablespoons of dough into a ball and place on your baking sheet. Leave 2 inches between each ball to prevent overspreading.
Bake for around 10-13 minutes. Bake the cookies until the edges are golden and the center of the cookies still look undercooked.
Leave the cookies on the baking sheet to cool for 5 minutes. They will finish cooking these last few minutes out of the oven.
Remove the cookies from the baking sheet and place on a cooling rack.