Preheat the oven to 350 degrees F. Prepare two baking sheets with parchment paper.
In a large mixing bowl, use a hand mixer or stand mixer to cream together the butter, granulated sugar, and brown sugar, until light and fluffy.
Add the egg and vanilla, and mix together again until well combined.
In a separate small bowl, stir together the flour, baking soda, and salt. Pour this into the other mixing bowl with the wet ingredients, and stir until well combined.
Fold in the oats, chocolate chips, and dried cranberries.
Use a small cookie scoop or heaping tablespoon to portion out cookie dough onto the prepared baking sheets. Bake at 350 degrees F for 11 to 13 minutes, or until the cookies are cooked through and the edges area light golden brown.
Let cool completely on the baking sheet (the cookies will crumble if you try to remove them when hot). Enjoy!