Pre-heat the oven to 350° F. Line a baking sheet with parchment paper and set aside.
In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.
In a separate large bowl, use an electric mixer to cream the butter and both sugars together until light and fluffy, about 1-2 minutes. Add the vanilla and egg, mixing until combined.
Gradually add in dry ingredients. Mix until everything is combined, but don’t over-mix. Use a rubber spatula to fold in the chocolate chips and chopped pecans.
Scoop dough onto the baking sheet with a cookie scoop (I used a large cookie scoop, so 3 tablespoon tablespoon of dough), leaving a few inches inbetween each cookie.
Bake for 9-12 minutes, until the edges are lightly golden brown but the middle is still underdone. Remove from the oven and press a few extra chocolate chips and/or pecans into the tops of the cookies as soon as they come out of the oven.
Let them sit on the pan for about 5 minutes and then transfer to a wire cooling rack, sprinkle with flaky sea salt (optional), and let them cool completely.