Preheat the oven to 350˚F and line an 8 by 8-inch baking pan with parchment paper so there is an overhang on all four sides.

Add butter and 1 cup of chocolate chips to a large microwave safe bowl. Melt in the microwave using 30 second intervals until butter and chocolate is melted. Whisk until smooth, and let cool slightly.

In a high speed blender combine eggs and dates and process until smooth, about 1 minute. There should only be small bits of date visual, about the size of sesame seeds. Any larger pieces should be mixed until broken down.

Pour the egg and date mixture into the melted chocolate and whisk for about 1 minute, or until well combined, then whisk in the vanilla extract. In a separate small bowl, sift flour, cocoa powder and salt together. Add flour to the chocolate mixture and fold gently with a rubber spatula until no streaks of flour remain. Fold in the remaining chocolate chips. Scrape the batter into the prepared pan and smooth into an even layer.

Bake until the top looks set, but the middle is still fudgy, 20-25 minutes. Let cool for about 30 minutes before slicing into 16 equal pieces.