Preheat your oven to 350 degrees Fahrenheit. Line two baking sheets with parchment paper.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

In a large bowl, cream together the softened butter, brown sugar, and granulated white sugar until light and fluffy using an electric mixer.

Add the egg yolks and vanilla extract, mixing until pale and fluffy.

Mix in the melted butterscotch chips until combined.

Add the dry ingredients to the wet mixture and mix until combined. Then fold in the butterscotch and chocolate chips.

Use a large cookie scoop to portion the dough onto the prepared baking sheets, spacing them 3 inches apart.

Bake for 10-11 minutes until lightly golden brown. Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

While cooling, optionally sprinkle extra chocolate chips, butterscotch chips, and flaky sea salt on top of each cookie for an extra indulgent touch.

Enjoy the irresistible goodness of these butterscotch chocolate chip cookies!