Grease bottom and sides of 13x9 baking pan.
In mixing bowl, combine cake mix (reserving 2/3 cup), butter and 1 egg.
Press in prepared pan. Bake at 350 for 15 to 20 minutes until golden brown.
Prepare filling by combining cake mix, brown sugar, corn syrup, vanilla and eggs, mix thoroughly. Pour filling over partially baked crust.
Sprinkle with pecans. Return to oven and bake an additional 30 to 35 minutes until filling is set.
Cool and cut into bars it makes about 3 dozen.