Preheat oven to 350 degrees and line a baking sheet with parchment paper.
Combine flour, cinnamon, baking soda and salt in a small bowl and set aside.
Cream together butter and sugars in a stand mixer or hand mixer, on medium speed for 3 minutes.
Add the egg and vanilla and mix well.
Add the dry ingredients to the wet ingredients and mix until just combined.
Stir in the oatmeal, apples and cranberries (if using) until combined.
Scoop the dough onto the prepared cookie sheet using a large cookie scoop or about 3 tablespoons of dough per cookie. Space the cookies at least 2 inches apart.
Bake for about 12-13 minutes until lightly golden brown.
Allow to cool on the baking sheet for 5 minutes and then cool completely on a wire rack.