In a large bowl, beat butter, granulated sugar, brown sugar, and vanilla until creamy. Works best with a mixer.
Add egg and beat well.
In a separate bowl, combine flour, baking soda, and salt. Gradually add this flour mixture into the butter mixture, beating well.
Stir in chocolate chips.
This next step is important. Refrigerate dough for at least one hour. This will harden the butter up again so that the cookies cook evenly.
Preheat oven to 350 degrees.
Drop cooled dough by rounded tablespoon (or use a medium sized cookie scoop) onto a parchment paper lined cookie sheet.
Slightly flatten the cookie dough balls with the palm of your hand.
Bake 11-13 minutes or until golden brown. Cool slightly before moving from cookie sheet to a wire rack for cooling.