Espresso and Lime

0 Preheat your oven to 350 degrees 
1 Line two flat baking sheets with parchment paper and set aside for now
2 Combine 8 tablespoons of softened butter with 1/2 cup of brown sugar and 1/3 cup of granulated sugar in a large bowl
3 Using an electric hand mixer on medium or stiff whisk, mix until fully combined
4 Add the egg, the egg yolk and 2 teaspoons of vanilla extract and mix to combine 
5 In a separate bowl, combine 2 cups of all-purpose flour, 1 tsp of cornstarch, 1/2 teaspoon of baking soda and 1/4 teaspoon of salt and then add to the remaining ingredients 
6 Mix until just combined
7 Add the chocolate chips and mix to incorporate 
8 Form about 2 teaspoons of dough into small round balls and place on the parchment lined baking sheets approximately 1 inch apart
9 Bake in a 350 degree oven for 5-7 minutes or until the edges are just set
10 Transfer the baking sheet onto a cooling rack and allow the cookies to cool for several minutes before enjoying
11 Store leftovers in an airtight container