Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper if desired.
In a mixing bowl, whisk together the flour, baking soda, and salt. Set aside.
In a separate large mixing bowl, beat the softened butter, granulated sugar, and brown sugar together until creamy (about 2-3 minutes).
Add the egg and vanilla extract to the butter mixture, and continue to beat until well combined.
Gradually add the dry ingredient mixture to the wet ingredients, mixing until just combined. Be careful not to overmix.
Fold in the chocolate chips with a spatula.
Spread the cookie dough evenly onto the prepared baking sheet into a round shape about ½ inch thick.
Bake in the preheated oven for 12-15 minutes, or until the edges are golden brown and the center is set.
Remove from the oven and let cool for a few minutes. Drizzle the chocolate sauce over the top before slicing.
Cut into 8 slices and serve warm or at room temperature.