Preheat the oven to 350℉/176℃. Line 2 baking trays with parchment paper. Melt the butter and allow it to cool for 15 minutes as you prep the rest of your ingredients.
1/2 cup + 1 tbsp unsalted butter
In a medium-sized bowl, add in flour, rolled oats, cinnamon, baking soda, baking powder, and salt. Stir to combine and set aside.
1 1/4 cups all-purpose flour, 1 1/2 cups rolled oats, 1/4 tsp cinnamon, 3/4 tsp baking soda, 1/2 tsp baking powder, 1/4 tsp salt
In a a large bowl, whisk the melted butter and brown sugar until well combined.
1 cup light brown sugar, 1/2 cup + 1 tbsp unsalted butter
Whisk in the egg, egg yolk, and vanilla extract until just combined.
1 egg, 1 egg yolk, 1 tsp vanilla
Add the dry into the wet and using a spatula, gently mix until just combined. Don't over-mix!
Mix in the butterscotch chips with a spatula, don't over-mix.
3/4 cups butterscotch chips
Scoop 6 cookies per tray (I used about 2 tbsp per cookie, I like using a cookie scooper), and space them 2-3 inches apart from each other.
Bake the cookies for 14-16 minutes or until the edges are a light golden brown and the center is soft.
These cookies are so good! Keep them on your counter for 3 days or in the fridge for a week in an airtight container. You can also freeze the cookies in a ziplock bag for up to a month and thaw them when ready to eat.