Heat oven to 350°F (325°F for dark or nonstick pan). Spray bottom and sides of 15x10x1-inch pan with baking spray with flour.
In large bowl, beat cake mix, oats, butter, orange peel and eggs with electric mixer on medium speed about 1 minute or until batter is thick. Stir in dates and walnuts. Spread in pan.
Bake 22 to 26 minutes or until top is golden brown and toothpick inserted in center comes out clean. Cool on cooling rack 10 minutes. Run knife around sides of pan to loosen bars. Cool completely, about 1 hour 30 minutes. For bars, cut into 8 rows by 6 rows. Store covered.