In a large bowl, cream butter and sugars. Beat in eggs one at a time, and then stir in vanilla. Combine flour, baking soda in a separate bowl. Slowly add flour mixture into the creamed mixture until just blended. Stir in oats and chocolate chips. Chill dough for 20-30 minutes.
Preheat oven to 325° F. Prepare cookie sheets by lining with parchment paper or silicon mats. Drop chilled dough by the teaspoonful onto prepared cookie sheets. Bake in preheated oven for 11-13 minutes - be careful not to overbake! Let cool on baking sheets for 5 minutes, then transfer to wire rack to cool completely.
Notes
Chocolate Chips can be replaced by semi-sweet morsels, chocolate mint pieces, dark chocolate, white chocolate... the possibilities are endless!