Preheat oven to 350 degrees and grease a 9x9 baking pan with non-stick cooking spray, set aside. (Can also line with parchment, lightly greased, if desired for easy removal of bars.)

In a large mixing bowl, add oil, eggs, orange zest, orange juice and mix until fluffy.

Add cake mix and mix until just combined.

Scoop out dough and spread in 9x9 pan.

Bake at 350 degrees for 20-25 minutes or until edges are firm but center is slightly soft.

Once they cool down, frost them with orange buttercream and devour!

Using mixer, combine the unsalted butter, orange juice, milk/cream, salt and powdered sugar together on low speed working up to medium speed for about 2-3 minutes.

Add orange zest (optional) and continue beating frosting to get frosting consistency needed. Add more powdered sugar if too thin, or add more juice or milk if too thick.

If desired, take some of the frosting and add a drop or two of the orange food coloring and mix together.

Frost the bars with the white frosting and add the orange colored frosting and swirl together to give it a creamsicle effect.

Garnish with orange slices if desired.