In a large mixing bowl, break up the cold, cubed unsalted butter with a wooden spoon or mixer for about 30 seconds until it starts to soften.

Add the granulated and dark brown sugars, mixing for about 1 minute until creamy.

Stir in the butterscotch chips for another 30 seconds.

In a separate bowl, whisk together the all-purpose flour, salt, and baking soda.

Gradually incorporate this dry mixture into the wet ingredients.

Add the whisked eggs and the butterscotch or butter extract.

Divide the dough into approximately 12 equal portions and roll each into a ball.

Freeze the dough balls for at least 1 hour.

Preheat your oven to 350°F (175°C).

Bake the frozen dough balls for 15 to 20 minutes.

Beat the softened unsalted butter for frosting until pale and fluffy, about 2-3 minutes, then mix in the powdered sugar and extract.

Frost the cooled cookies generously.