In a large bowl whisk together the cake, mix, eggs, water and oil according to the directions on the box.
Pour the batter into the prepared pan.
Bake 25-30 minutes, or until toothpick inserted in center comes out clean. Cool slightly.
Using a large straw or end of a wooden spoon, poke holes all over the cake.
In a small bowl, whisk the boiling water and orange gelatin until dissolved.
In a large mixing bowl, whisk together the cold milk and vanilla pudding.
Whisk the orange Jell-O into the pudding mixture until well combined.
Pour the filling all over cake, using a spoon to get the filling into all the holes.
Spread the whipped cream evenly over the top of the cake.
Garnish with mandarin oranges and mint.
Refrigerate at least 1 hour.
Notes
Sprinkles: Top the cake with sprinkles for a fun finish.
Candy Orange Slices: Instead of real orange slices, use candy orange slices. This will allow you to store the cake at room temperature instead of refrigerating it, letting it keep its moisture.
Vanilla Flavor: To heighten the flavor, add some vanilla extract and orange zest to the cake batter.
Layers: For a multi layer cake, double the recipe to add another layer.