Place flour in a microwave safe bowl and heat for 1 minute. Stir and allow to cool. (This kills any potential bacteria since we are not baking!)
Spray a 9x9 pan with cooking spray and then line with parchment paper.
Using a hand mixer, beat the butter, sugars and vanilla until smooth.
Add your salt to the flour, and then beat those into the butter mixture until smooth.
Stir in 1 cup of mini chocolate chips.
In a separate bowl, combine your melted chocolate and sweetened condensed milk and stir well. It will thicken up quite a bit, so work quickly!
Fold the chocolate mixture into the cookie dough mixture. Stir well (this will take a little muscle!) until you don't have chunks of dough mixture left.
Pour into your prepared pan, smooth and top with the remaining chocolate chips.
Place in the fridge and allow it to cool for at least 2 hours, until set and firm.
When you're ready to serve it, simply lift the parchment out and cut it into squares!