1. Bake brownies according to package directions in a 9x13-inch pan; let cool completely. Spread with chocolate frosting and cut into 12 rectangles.
2. Cut gummy worms into pieces and press into the top and sides of brownie.
3. Microwave Tootsie Rolls for 3 seconds on high. Roll each into a 1/2x3-inch strip. Cut with scissors to straighten; repeat with the remaining Tootsie Rolls. Place strip on brownie to make the binding. With vanilla tube frosting, pipe horizontal lines to resemble the pages of a book. Pipe two white dots on the gummy worms head and add mini chocolate chips as the eyes.