01 -  In a large mixing bowl, beat the unsalted butter and brown sugar until light and fluffy. 
 02 -  Add the egg and vanilla extract to the bowl and mix until well combined. 
 03 -  Mix in the all-purpose flour and rolled oats, stirring just until incorporated. 
 04 -  Gently fold the chocolate chips into the dough. 
 05 -  Scoop tablespoon-sized portions of dough onto a baking sheet, spacing them evenly. Bake at 350°F for 10 to 12 minutes until golden at the edges.