Preheat the oven to 350 F / 180C.
Line a baking sheet with parchment paper or aluminum foil. I used one large sheet and one medium sheet.
Sift together flour, salt, baking soda and cinnamon powder in a bowl.
In a separate bowl beat soft butter, brown & white sugars till creamy and fluffy.
Add egg, vanilla extract and beat until combined.
Add flour mixture to wet ingredients and beat until well combined.
Fold in oats and butterscotch chips.
Drop spoonful of batter onto a cookie sheet or shape cookies with hand and place on cookie sheet. I prefer the latter.
Bake for 8 – 12 minutes for chewy cookies and longer for crispy cookies. In my oven it takes 12 minutes. Bake the first batch while you shape the second batch of cookies. It is is ok to keep the second batch on the countertop while the first batch bakes. But not leave it for too long.
For crispier cookies, bake for extra 2-3 minutes. Mind you cookies continue to bake even after removing from the oven.
Let the cookies cool for few minutes on cookie sheet, transfer to cooling rack and let cool completely.
Store in airtight container.