Take the butter out of the fridge and bring it to room temperature. Juice the lemon into a bowl and set aside.

In the bowl of a stand mixer add the butter and the shortening.

Mix on medium speed until they are creamed together and get creamy and fluffy. If needed scrape the sides of the bowl to get all of the mixture to the bottom of the bowl.

Turn the mixer speed to the lowest setting and slowly as in the powdered sugar.

Turn the mixer down to the lowest setting and slowly incorporate the powdered sugar into the shortening mixture.

Once you have added all the powdered sugar to your mixture, add in the vanilla extract and then the lemon juice.

Turn the mixer up to medium-high speed and continue mixing for 10 minutes until light and fluffy.

Once it is fully whipped you will want to check the consistency to see if it is what you need. If you need to make it thicker you can, if you need to make it thinner you can.