Put the marshmallows in a big microwave safe bowl. I have an 8 cup Pyrex that is perfect for this.
Heat for 1-2 minutes, until soft and puffy.
Whisk the soft marshmallows with 1/2 cup soy creamer until smooth. You may have to return the mixture to the microwave for another minute or so to get the marshmallows to fully melt into the creamer.
Add the remaining 2 1/2 cups of creamer, sugar and oil. Whisk until smooth and the marshmallows are all melted.
Cool the mixture down in the freezer or refrigerator before pouring into an ice cream maker to freeze. I have a Cuisinart Ice Cream Maker that is wonderful.
In a small bowl, smash the Oreos up with some blue food coloring until the Oreos are small chunks and the blue color is spread around pretty well. Add the jimmies into the bowl and set aside.
Scoop the frozen ice cream out of the ice cream maker into the container you plan to freeze it in. Stir the cookie mixture into the ice cream. Don’t mix it around too much, or the vanilla ice cream will turn blue and the jimmies will get smashed up. Freeze and serve!