Preheat oven to 350 degrees F; line cookie sheets with parchment paper.
In a large bowl, combine all ingredients until smooth, using either an electric mixer or a spoon. Mix in more jimmies, if desired. Shape dough into balls that are slightly less than a tablespoon in size, and place two inches apart on your cookie sheets.
Bake cookies for 10 to 12 minutes or until the bottoms of the cookies just start to brown; the centers will likely still be a little soft and the cookies will be light in color. Cool for a few minutes, then move to a wire rack to cool completely.
Store in an airtight container for up to a week.
Notes / Variations
This basic recipe can be used with any type of cake mix, changing up your add-ins as desired.