Crust: Preheat oven to 350°F Cream crust ingredients together. Press firmly into greased 9" square pan. Bake for 10-15 minutes or until golden. Let cool while preparing filling.
Centre: In a medium saucepan, heat sweetened condensed milk and butter over low heat for 5-10 minutes or until slightly thickened. Stir constantly to prevent burning. Spread over crust. Bake 12-15 minutes or just until golden.
Top: Sprinkle chips evenly over the filling. Bake 2 minutes, remove from oven and spread with spatula. Sprinkle toffee bits (adjust quantity to your liking) and press lightly into the melted chocolate. Cool in refrigerator.