Preheat your oven to 350°F and line a baking sheet with parchment paper.
In a medium bowl, whisk together the flour, baking soda, baking powder, and salt. Set this aside.
In a large bowl, combine the melted but cooled butter with both the brown sugar and granulated sugar. (Make sure the butter isn’t too hot; it can be a little warm.) Whisk the mixture for 1-2 minutes until it forms a smooth, paste-like consistency.
Add the egg and vanilla extract to the sugar mixture and whisk until everything is well combined.
Fold in the dry ingredients using a rubber spatula, leaving a few streaks of flour in the batter. Then, add the chocolate chips and continue folding until the dough is just combined, being careful not to overmix.
For perfectly sized medium cookies (my personal favorite), use a medium 2-tablespoon cookie scoop. For larger cookies, opt for a 3-tablespoon scoop or a 1/4 cup measuring cup. Place 5-6 cookie dough portions onto the prepared baking sheet, ensuring enough space between them.
Bake for 10-15 minutes, adjusting the time based on the size and your texture preference—bake on the lower end for softer, gooey cookies, and longer for a firmer, chewier texture.The cookies are done when the edges are golden but the centers remain pale and puffy. While still warm, sprinkle with a pinch of flaky sea salt for added flavor.
Transfer the cookies to a cooling rack and bake the remaining dough. Let the cookies cool for about 20 minutes before enjoying. They're best served warm when the chocolate chips are still slightly melted.