Preheat oven to 350°. Arrange pecans in a single layer in a shallow pan. Bake pecans 5 to 7 minutes or until lightly toasted and fragrant. Remove from oven. Reduce oven temperature to 300°.
Stir together cake mix, pecans, 1 egg, and butter; press mixture into bottom of a lightly greased 13- x 9-inch pan.