Preheat the oven to 350 F. In a medium bowl, whisk together flour, salt, and baking soda. In a large bowl, mix together butter, peanut butter, granulated sugar, and brown sugar until fluffy.
Add in the egg and vanilla extract, and mix until smooth. Add in the flour mixture and mix until it is fully combined. Divide the cookie dough between two bowls, and add green food coloring to one bowl and blue to the other.
In a shallow dish, whisk granulated sugar and ground cinnamon together. Take a small amount of cookie dough from each dough and roll together into balls. Roll in the cinnamon sugar mixture and place onto a large ungreased baking sheet at least 2-inches apart. Bake for 10-12 minutes.
