heat oven to 350°F

combine flour, powdered sugar, cocoa, and baking soda in medium bowl; cut butter until mixture is crumbly. press onto bottom of ungreased 13x9x2 inch baking pan. bake for 15 minutes.

beat cream cheese until fluffy. add sweetened condensed milk, eggs and vanilla; beat until smooth. stir in 3/4 cup toffee bits. pour mixture over hot crust. bake 20-25 minutes or until set and edges begin to brown.

remove from oven. cool 15 minutes. sprinkle remaining toffee bits evenly over top. cool completely. refrigerate several hours or until cold.