Using a stand mixer (or hand mixer in a large bowl) combine cream cheese, butter, and peppermint oil on medium speed until smooth.
Add the powdered sugar 1 cup at a time with the mixer on low speed. After 8 cups of powdered sugar have been added, check the consistency. It should feel like dough and not be sticky.
If the mixture is still sticky, gradually add up to 1 more cup of powdered sugar until little balls can be easily formed.
If you want to color the mints, divided the dough evenly by the number of colors you want to use. Add 1-3 drops of food coloring to each ball of dough and knead until colored. Add more food coloring until your desired shade is reached. If the dough becomes sticky, add 1 tablespoon of powdered sugar at a time as needed.
Roll the dough into little balls and set them on parchment paper. Cover the remaining dough while you roll pieces. If it becomes too dry, knead with your hands until smooth.
Use a fork to flatten the dough right after rolling the ball. This will help prevent the mints from having a cracked surface.
Allow the mints to dry on parchment paper for about 2 hours before freezing or refrigerating in an airtight container.
Notes
Recipe yield will vary slightly depending on the size of the mints.Peppermint oil is very potent. It's better to start with less and add more to taste. If you want to make these mints in other flavors start with 1/4 teaspoon of extract (like lemon, root beer, or almond) and adjust to taste from there. I recommend using gel food coloring. It has a more intense color and you won't need as much to color the dough. This also means you won't need to add as much powdered sugar to keep the mint dough from getting sticky.