Using an electric mixer on medium-low speed or by hand, cream butter and sugar together until smooth and fluffy.
Stir in oats, baking soda, and salt until well mixed. Stir in chocolate chips and sour cream until combined.
On a baking sheet lined with a silicone mat or parchment paper, scoop cookie dough with a medium disher or tablespoon. Flatten dough balls into cookie shapes because they will not spread during baking. You only need to space cookies about 1″ apart.
Bake in preheated oven for 12 minutes, or until bottoms and edges have browned. Allow to cool on pan for a few minutes, and then transfer to a wire rack to cool completely.
Store cookies in the refrigerator if they aren’t all eaten within a few hours.