Heat oven to 355F. Lightly spray 9×13 pan with non-stick spray.
Pour juice from oranges into a 3/4 cup measuring cup. (If the oranges are packed in water or simply if you prefer, use orange juice instead.) Combine cake mix, eggs, oil, and juice in large mixing bowl. Beat with electric mixer or by hand until blended well. Fold in mandarin orange slices.
Pour batter into prepared pan and bake for approximately 45 minutes or until toothpick inserted in center comes out clean. Frost with Namaste Toffee Vanilla Frosting – yum!
Use a neutral tasting vegetable oil that is safe or your needs.