Preheat oven to 350° F and grease 13 x 9-inch baking pan.

Beat brown sugar, flour and margarine in a large mixer bowl until well blended and creamy.

Press evenly onto bottom of 9x13 pan.

Bake at 350 for 20 25 min or until light golden.

Remove from oven to wire rack while preparing filling.

Heat sweetened condensed milk and margarine in heavy pan,stirring constantly over med heat for 5-10 min or until thickened.

Spread over cooled crust.

Bake at 350 for 12-15 min or until light golden.

Sprinkle chocolate chips evenly over the top.

Bake for 2 min longer or until chocolate is shiny and soft.

Remove from oven and spread chocolate evenly.

Sprinkle toffee bits on top,pressing lightly into chocolate.

Cool completely and cut into bars.

Cover and store at room temperature.

In warm days, bars may be stored refrigerated.

Bring to room temperature before cutting.