Preheat oven to 350 degrees F (175 degrees C). Line a 9x13 inch pan with aluminum foil and grease the foil. Melt chocolate and butter together in the microwave, stirring occasionally until smooth; set aside to cool.
In a large bowl, beat eggs, sugar and vanilla until frothy, stir in the chocolate mixture. Combine the flour and salt ; blend into the batter. Fold in the chocolate chips and toffee pieces. Spread evenly into the prepared pan.
Bake for 28 to 32 minutes in the preheated oven, until a toothpick inserted in the middle comes out slightly sticky. Cool before cutting into bars.
