Preheat the oven to 350F and line a large baking sheet with parchment paper.
In a medium-sized bowl, whisk together the flour, baking soda, baking powder, and kosher salt until well combined.
In a large mixing bowl, combine melted butter with both sugars until it reaches a paste-like consistency, then add in the egg and vanilla extract, whisking until smooth.
Gradually pour the dry ingredients into the wet mixture, using a rubber spatula to fold them together until just combined. Fold in chocolate chips gently.
Using a large cookie scoop or measuring cup, portion out your dough onto the prepared baking sheet and bake until golden around the edges yet soft in the center.
Remove from oven, top with additional chocolate chips and flaky sea salt if desired, and let cool on a wire rack for about 20 minutes.