To begin, if your butter and eggs have been kept refrigerated, then you’ll need to let them reach room temperature by keeping them out on the counter for around an hour, although if you’ve kept them at room temperature anyways, then you can begin straight away.
In a large bowl, you’ll want to combine butter and sugar together, this is best done using a hand mixer, and should only take around 2 to 3 minutes before they are fully combined
With your mixture made, now add in the vegetable oil, and then ensure that it is all combined before adding in your powdered sugar
With the powdered sugar added, continue to cream the mixture for another 2 to 3 minutes until the mixture is both fluffy and light
Add in both the vanilla extract and the egg, and cream for one final minute
In a different bowl, mix together the all-purpose flour, baking soda, and the cream of tartar. Ensure that you add the baking soda a little bit at a time, ensuring each amount is mixed together thoroughly before adding more.
Then mix in the unicorn sprinkle mix in with the cookie dough
A small cookie scoop is then used to scoop up balls of dough onto your baking sheets. Just be sure to line your baking sheets before you add the dough though.
Place the dough on the baking tray into the oven at 350 degrees Fahrenheit, and then bake it for between 7 to 9 minutes.
Take your cookies out of the oven, and then allow them to cool on the sheet for a couple of minutes before transferring them to a cooling rack before they cool completely.