Pre-heat the oven to 350°F.
Cream (or mix) together the butter, brown sugar, and pure cane sugar.
Add the eggs and vanilla extract to your mixture, and mix well.
Stir the baking soda into your buttermilk (or sour milk) and set aside.
Sift together the dry ingredients, including the flour, salt, and ground cinnamon.
Mix the dry ingredients into the creamed mixture, alternating with the buttermilk.
Fold in the oatmeal and chocolate chips, mixing them into the dough.
Using a cookie scoop, drop cookies onto your cookie sheet, pressing/patting the cookies somewhat flat with your fingers or the flat bottom of a glass.
Bake for 12 to 15 minutes, or until the cookies turn a nice golden hue.
When you remove each batch from the oven, remove the cookies from the cookie sheet and allow them to cool on a wire rack.
Serve with a nice tall glass of ice cold milk.