Preheat the oven to 375 degrees. Line 2 baking sheets with parchment paper and spray lightly with cooking spray, then set aside. In the bowl of a food processor, combine vanilla, cocoa, cannellini beans and the agave syrup, then blend mixture until smooth, about 3 minutes, scraping down the side of the bowl halfway through blending. In the bowl of a mixer fitted with a whip attachment, beat the egg whites until they form soft peaks. Gradually beat in the Splenda. Continue to beat the whites until creamy and nearly stiff. Add 1/3 of the egg white mixture to the cocoa bean mixture in the food processor. Blend to combine, about 30 seconds. In 2 batches, fold the lightened cocoa mixture into the egg whites until they are almost fully combined. Add cacao nibs to the batter. Fold batter until cacao nibs are evenly dispersed and cocoa mixture is completely incorporated. Drop by mounded spoonfuls of batter onto the prepared sheets. Spread batter out to form cookies about 2 1/2 inches in diameter. Sprinkle the chocolate chips on top of cookies. Bake for about 20 minutes, rotating the pans one turn, halfway through baking. Using a metal spatula, transfer cookies to wire racks to cool.