In a medium bowl, cream together the butter, white sugar, and brown sugar.
Beat in eggs one at a time, then stir in the vanilla.
Combine flour, baking soda, salt and cinnamon together and then stir these into the creamed mixture.
Mix in the oats.
Cover and chill the cookie dough for at least one hour.
Pre-heat the oven to 375 degrees.
Grease cookie sheets.
Roll the cookie dough into walnut-size balls and place them 2 inches apart on the cookie sheets. Flatten each cookie with a large spoon dipped in sugar.
Bake for 8 to 10 minutes in the pre-heated oven.
Allow the cookies to cool on the baking sheets for 5 minutes before placing them on a wire rack to cool completely.
