Pre-heat oven to 425 degrees or 400 convection with rack in center of oven.
In the bowl of a stand mixer, or a large mixing bowl, place cut butter. Mix on low until butter is broken up.
With the mixer on low, add sugars. Blend until there are no visible chunks of butter, about 1 minute on low or medium low.
Add eggs and mix until smooth on low or medium low.
Stop mixer and add flour, cornstarch, oats, baking soda, salt and cinnamon.
Pulse the mixer until the wet and dry ingredients are incorporated. This will take about 10 pulses of the mixer (quick on -off motion) . Then mix on low until the flour disappears.
Mix the raisins in using the pulse motion again.
Using a kitchen scale, measure out 6 oz portions, do not compact the dough or use a cookie scoop, the cookie is meant to have a rough shape! Stack the cookie high so it will still be thick after baking.
Place the cookies on a cookie sheet or jelly roll pan 4-5 per sheet.
Bake for 6-7 minutes or until the cookie is barely set and golden on top.
Remove from oven and let sit for at least 30-60 minutes to allow the cookie to set up.
Notes
-The butter should be barely soft.I can see an indentation when I push my finger into the side of the butter, but the butter will not totally collapse. Either leave the butter on the kitchen counter for about 30 minutes before using or microwave the butter. I remove my butter straight from the refrigerator and microwave it for 18-20 seconds, My microwave is not very powerful, most microwaves will probably need about 10-12 seconds to achieve the right result! -The size of the eggs will determine the amount of moisture in the cookie to some degree. I recommend using large or extra large eggs. The extra large eggs from Costco are HUGE, so you may need to add a bit of flour 1-2 tablespoons if the dough is wet and sticky after mixing all ingredients together. Fold in the extra flour with a large spoon or spatula. -sea salt is recommended but not absolutely necessary. I like the flavor of sea salt as opposed to table salt. The next time you have both sided by side, pour a little in your hand and taste the difference! -You may substitute 2 cups of chocolate chips ( I recommend dark of semi sweet chocolate) for the raisins.