1. Heat oven to 350*F. Grease 13X9-inch pan. In large bowl, combine cake mix, butter and egg; mix well with pastry blender or fork. Press mixture in bottom of greased pan. Bake for 7 minutes.
2. Meanwhile, in medium bowl, combine condensed milk, vanilla and 1 egg; mix well. Stir in toffee bits and pecans.
3. Remove pan from oven; pour filling evenly over warm base. Return to oven, bake an additional 22 to 30 minutes or until filling is set. Cool 1 hour or until completely cooled.Cut into bars. Store in refrigerator.
NOTES : If you can't find chocolate-coated toffee bits, coarsely chop = four 1.4-ounce Heath or Skor bars. These bars are easier to cut after they = have been refrigerated.