For the brownies, coat 20 disposable 4-inch pie pans with cooking spray; place on 2 baking sheets. In a medium bowl, whisk the flour, cocoa powder and salt. In a medium saucepan, heat the chocolate and butter over medium, stirring until smooth. Off heat, whisk in both sugars.
Whisk the eggs, 1 at a time, into the chocolate mixture. Whisk in the vanilla, then sprinkle with the dry ingredients. Fold until almost combined. Fill each pan with 1/4 cup batter; smooth the tops. Cover; refrigerate 3 hours.
For the cookies, in a medium bowl, whisk the flour, baking soda and salt. Using an electric mixer, beat the butter and sugars on medium speed, occasionally scraping down the bowl, until smooth, 3 minutes. Add the egg; beat to blend. Beat in the vanilla. Add half the dry ingredients; beat to blend. Add the remaining dry ingredients; beat to blend. Fold in the chocolate chips. Cover; refrigerate 3 hours.
Preheat the oven to 350 degrees . Roll 2 tbsp. cookie dough into a ball; flatten slightly. Press into the center of one of the brownie batter pans. Repeat with the remaining dough and batter. Bake, rotating sheets halfway through, until the cookies are golden and the brownies are set, 20 to 22 minutes.