Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper.
In a large bowl, whisk together the melted butter, granulated sugar, and light brown sugar until smooth and combined.
Add the egg and vanilla extract to the butter and sugar mixture and whisk until fully incorporated.
In a separate bowl, sift together the all-purpose flour, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, stirring gently until just combined. Do not overmix.
Fold in the semisweet chocolate chips evenly throughout the dough.
Using a tablespoon or cookie scoop, drop small rounded spoonfuls of dough onto the prepared baking sheets, spacing them about 2 inches apart. Flatten each dough ball slightly with the back of a spoon or your fingers to encourage thinness.
Bake in the preheated oven for 10 to 12 minutes, or until the edges are golden brown and the centers are set but still slightly soft.
Remove the baking sheets from the oven and allow the cookies to cool on the sheets for 5 minutes before transferring them to a wire rack to cool completely.
Store cooled cookies in an airtight container at room temperature for up to 5 days.