Preheat the oven to 350 F. In a medium bowl, whisk together flour, salt, and baking soda. In a large bowl, combine butter with brown sugar and granulated sugar until fluffy. Add in the egg and vanilla extract, and mix until smooth.
Add in the flour mixture, and mix until a thick dough forms. Divide the cookie dough into two bowls and mix blue food coloring into one and green in the other. Mix 1/2 cup chocolate chips into each cookie dough.
Take a small amount of each cookie dough and roll together into balls. Place onto a large ungreased baking sheet at least 2-inches apart. Bake for 10-12 minutes.