In a medium bowl, whisk together the flour, salt and baking soda.
In a stand mixer fitted with the paddle attachment, cream the butter with the sugars until light and fluffy, 2 minutes. With the motor running, add the eggs, one at a time and scraping the sides of the bowl as needed. Add the vanilla and mix to incorporate.
Add the dry ingredients and mix slowly until a smooth dough forms. Remove the bowl from the mixer and fold in both chocolates with a spatula. Cover with plastic wrap and refrigerate for at least 2 hours and preferably overnight.
Preheat the oven to 350° and line 2 sheet pans with parchment paper. Scoop the cookie dough into twenty 1/4-cup balls. Working in 2 batches, bake the cookies, placing 5 cookies on each tray 2 inches apart from each other, until golden brown, about 16 minutes. Let cool slightly, then serve warm.