Melt the butter over medium low heat in a small sauce pan. Let cool to room temperature.
Meanwhile, sift or mix together flour, salt, baking powder and baking soda in a medium bowl. In a small measuring cup, add the egg, egg yolk, milk and vanilla extract, whisk together and set aside.
Add the cool butter and sugar in a stand mixer bowl and beat with a paddle attachment on medium speed until fluffy and lighten in color, about 2 minutes.
Add the egg mixture to the butter/sugar mixture and beat on medium speed for another 2 minutes.
Reduce the mixer to low speed and gradually add the flour mixture, scraping the side and bottom of the bowl as necessary.
Once all the flour is incorporated, turn the mixer speed to stir and add the chocolate chips, mix until the chips are evenly distributed.
Use a large ice cream scoop (2 oz) to portion the cookie dough onto a parchment paper lined baking sheet or large container. Cover well and refrigerate for at least 1 hour or overnight.
Preheat oven to 350°F.
Place pre-portioned cookie dough on a parchment paper line baking sheet, 2" apart. Bake for 13-15 minutes. Bake in 2 to 3 batches.
Let cool on the baking sheet for 5 minutes then transfer with a spatula to cool completely on a wire rack.