Preheat oven to 375 degrees Fahrenheit (190 degrees Celsius).
In a small bowl, whisk together the flour, baking soda, salt, and cinnamon.
In a large mixing bowl, cream the softened butter, granulated sugar, brown sugar, and vanilla extract until the mixture is light and fluffy.
Add eggs one at a time, beating well after each addition to ensure proper emulsification.
Gradually add the dry flour mixture to the wet ingredients, mixing at a low speed until just combined.
Stir in the old-fashioned oats and butterscotch chips by hand using a spatula until evenly distributed.
Drop the dough by rounded tablespoonfuls onto ungreased baking sheets, spaced approximately 2 inches apart.
Bake for 8 to 10 minutes or until the edges are golden brown.
Cool the cookies on the baking sheet for 2 minutes before transferring them to a wire rack to cool completely.