Preheat your oven to 350℉ and line a baking sheet with parchment paper.
Add the butter and sugar to a large bowl and cream the butter at high speed until light and fluffy (3-5 minutes)Scraping down the sides and bottom of the bowl as needed.*Be careful not to let the butter get too warm, it should just be slightly softened so it whips with the sugar. If it's too warm, the cookies will spread out and not rise.
Add the eggs and vanilla extract to the creamed mixture and whip at low speed increasing to high and mix until light and fluffy.Scraping down the bottom and sides of the bowl as needed.
Add the flour, baking soda, salt, and cinnamon to the mixture and mix on low until fully combined.
Fold the oats and cranberries into the mixture by hand, mixing just enough to incorporate.
Scoop about 2 tablespoons of dough for each cookie and place them on the prepared cookie sheet, 2-3 inches apart.
Place the cookie sheet on the center rack of the preheated oven and bake for 8-10 minutes or until slightly golden.Repeat the process until all of the cookie dough has been used. Keep the cookie dough refrigerated while waiting to bake.
Let the cookies cool on the pan for 2-3 minutes then carefully move them to a wire rack to finish cooling.Store the cookies in an airtight container at room temperature for up to 7 days.