In large saucepan, heat butter, brown sugar, cocoa powder and salt, stirring occasionally, until butter is completely melted. Remove saucepan from heat. Quickly stir in eggs and vanilla; stir until combined. Add flour; stir until combined and batter is very shiny; mixture will still be very warm. Stir in chocolate chips, continuing to stir until completely melted. Add 1-1/3 cups chopped Candy Melts candy; stir just until combined. Pour into prepared pan.