Preheat your oven to 350°F (175°C) and prepare two baking sheets by lining them with parchment paper to prevent sticking.
In a large mixing bowl, using a hand mixer or a stand mixer with a paddle attachment, beat the softened butter, packed brown sugar, and granulated sugar together on medium speed until the mixture becomes light, fluffy, and creamy—approximately 2-3 minutes.
Add one egg at a time, mixing well after each addition to ensure they are fully incorporated. Then, stir in the pure vanilla extract, mixing just until combined.
In a separate bowl, whisk together the all-purpose flour, baking soda, and fine sea salt. Gradually add this dry mixture to the wet ingredients, mixing on low speed or folding with a spatula until just combined. Avoid overmixing to keep the cookies tender.
Gently fold in the butterscotch chips and chopped pecans with a spatula, ensuring they are evenly distributed throughout the cookie dough.
Using a cookie scoop or a rounded tablespoon, drop generous mounds of dough onto the prepared baking sheets, making sure to leave at least 2 inches between each mound to allow for spreading during baking.
Bake in the preheated oven for 10-12 minutes, or until the edges are golden brown and the centers appear slightly underbaked for that chewy texture.
Carefully remove the baking sheets from the oven and let the cookies cool on the sheets for about 5 minutes. After that, use a spatula to transfer the cookies to wire racks to cool completely.
Notes
For an extra special touch, serve the cookies warm with a drizzle of melted butterscotch sauce on top and a sprinkle of freshly chopped pecans.