In the bowl of a stand mixer fitted with a paddle, beat the cold butter until creamy. Add the sugar and continue to beat until it is mixed in. Gradually add the eggs and vanilla and continue beating with the paddle on medium until mixed, scraping sides of bowl once or twice. The coolness from the eggs may make little bits of butter firm up again so the creamy mixture may appear lumpy.
Meanwhile, in a separate bowl, mix the flour (make sure you weighed it), salt, baking soda, baking powder and cinnamon. With the mixer on medium-low (or by hand with a heavy duty rubber scraper), gradually add the flour mixture stirring just until mixed. Stir in the oatmeal, then stir in the raisins and nuts.
Empty the batter onto a large flat surface and make sure all the ingredients are evenly incorporated. Divide into 10 or 12 raggedy pieces. Arrange the pieces on a foil lined baking sheets or a couple of plates and chill dough until it's firm enough to handle. Shape into tight balls, then continue to chill for several more hours or overnight if you have time.
Preheat oven to 375 degrees F. If you are using convection, preheat to 350 F convection. If you plan on chilling the dough, skip this step. Chilling the dough will help make the cookies thicker.
Arrange cookies (I recommend baking 1 or 2 first to nail down your time) on a heavy duty cookie sheet. Bake on center rack for 18 minutes at 375 or 16 minutes at 350F convection. Let cool for about 5 minutes on the cookie sheet, then remove and finish cooling on a rack. When cool, you can eat OR you can freeze the cookie and thaw them for a better texture.