Mix together the cake mix, milk, butter, and eggs according to the package directions for the cake mix you're using.
Bake the cake according to the package directions, and allow it to cool for 10-15 minutes. Your cake is fully baked when a cake tester or toothpick inserted into the center comes out clean.
Meanwhile, while your cake is cooling, mix the Jello mix with boiling water, mixing 'til the Jello powder is fully dissolved.
Then stir the cold water into the Jello mixture.
Poke holes all over the top of the cake with a fork. Don't poke too many holes, or your cake will be completely orange, and we're going for orange stripes in the cake instead.
Slowly pour the Jello mixture over the entire cake, and allow the cake to finish cooling.
Once your cake has cooled, whisk together the pudding mix, milk, and orange juice 'til the pudding thickens.
Fold the whipped cream into the pudding mixture with a spatula. (By fold, I mean gently mix by hand.)
Spread the frosting onto your completely cooled cake, and chill for at least 2 hours before serving.
Garnish each slice with mandarin oranges before serving.