Preheat oven to 350 degrees F. and lightly grease or line a baking sheet with a silicone liner or parchment paper.
Whisk together the flour, baking soda, salt, and cinnamon in a small bowl; set aside.
In a large bowl, combine the butter, granulated sugar, brown sugar, eggs, and vanilla extract and beat until smooth. Add the flour mixture to the butter mixture and stir until smooth.
Add the oats and use a sturdy spoon to stir until well combined. Add the butterscotch and chocolate chips and stir until they are incorporated throughout the dough. The dough will be quite stiff.
Drop by rounded tablespoonfuls on baking sheet, 2 to 3 inches apart, and flatten balls slightly with the palm of your hand.
Bake just until edges are lightly browned, about 8 to 9 minutes.
Remove from oven, cool on the pan for 1 minute, and then transfer to a wire rack to finish cooling. Makes about 4 dozen cookies.
Notes
Store cookies at room temperature in a tightly sealed container. For the best flavor and texture, eat within 5-7 days.Cookies can be frozen, tightly wrapped, for up to 2 months. Thaw in the refrigerator overnight before eating.