Preheat the oven at 300 F / 150 C for 10 minutes.
Mix together all the dry ingredients and whisk to combine.
In a clean bowl, add and cream the butter and the sugars, using the mixer. Whisk until the butter and sugars are compleley incorporated and the mixture begins to get pale. Add the egg and whisk until the mixture gets fluffy.
Pour in the vanilla extract and the melted chocolate. Whisk until the chocolate is completely mixed in. Now, add the dry ingredients to it. Mix it using a spatula or mixer. Careful not to overmix.*
Tip in the chocolate chips and mix using the spatula until completely mixed in. Cover the bowl with a lid and chill in the refrigerator until the oven gets preheated.
Line a baking tray with parchment paper or silpat. Remove the cookie dough from the refrigerator.Using a small ice cream scoop, scoop out portions of cookie dough onto the lined baking tray. Leaving a space of 2 inches in between the balls and do not flatten it.
Place the tray in top rack of the oven and turn to bake mode*. Let it bake for 13-16 minutes dependign uopn your oven.*
Once done, remove from oven and let it cool on the tray for 10 minutes. Move the cookies to a cooing rack and let the cookies cool down completely.
Serve the Double Chocolate Chip Cookies with milk or ice cream!