Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy.
Add the egg and vanilla extract to the mixture, and stir until combined.
In another bowl, mix the rolled oats, flour, baking soda, cinnamon, and salt.
Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Fold in the dried cranberries until evenly distributed.
Drop spoonfuls of the cookie dough onto the prepared baking sheet, spacing them about 2 inches apart.
Bake in the preheated oven for 10-12 minutes or until the edges are lightly golden.
Remove from oven and allow cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.