1. Heat oven to 350°F. Line cookie sheets with parchment paper.
2. Stir together cookie mix and flour; add butter and egg yolk. Stir until crumbly. Add 3/4 cup toffee bits; work with hands until dough forms a ball. (Dough will feel very much like pie dough.)
3. Divide dough into 4 equal balls. One ball at a time, flatten into 7-inch circle approximately 1/4-inch thick on prepared cookie sheet. Cut circle into 12 equal wedges; do not separate dough.
4. Bake 10 to 12 minutes or until edges are a light golden brown. Cool 3 to 5 minutes; recut wedges and separate slightly. Slide parchment paper with cookie wedges to wire rack. Cool completely. Repeat with remaining balls of cookie dough.
5. Line tray with wax paper. Place milk chocolate chips in microwave-safe measuring cup. Microwave at MEDIUM (50%) 1 minute; stir. If necessary, microwave at MEDIUM an additional 30 seconds at a time, stirring after each heating, until chocolate is melted and smooth when stirred.
6. Dip narrow end of each cookie wedge into melted chocolate. Shake gently and slide cookie bottom against edge of container to remove excess chocolate. (If necessary, reheat chocolate at MEDIUM for a few seconds.) Place on prepared tray. Before chocolate sets, sprinkle with remaining toffee bits or combination of toffee bits and chopped nuts. Makes 48 cookies.
Tip: Any leftover chocolate and toffee bits can be used to coat pretzel rods or other cookies.