**If planning to bake these right away without chilling the dough, preheat the oven to 375 degrees and line two large baking sheets with a Silpat or parchment paper and set aside.
In a large bowl if using a hand mixer, or bowl of stand mixer fitted with the paddle attachment, cream together the butter, both sugars, and peanut butter until fluffy and pale in color. About 5 minutes.
Add the eggs and vanilla to the sugar mixture and beat on medium speed for 2 minutes, until combined.
Add the flour, oats, baking soda, salt, and cinnamon to the mixer and meat on medium speed for 2-3 minutes, until well combined. Stir in the chocolate chips if using.
OPTIONAL: For a thicker cookie, place the dough in the refrigerator and chill for 30 minutes.
Drop the dough by Tablespoon-fulls onto prepared baking sheets.
Bake in preheated oven for 12-15 minutes, just until lightly golden.
Remove the cookies from the oven and allow them to cool on the pan for 5 minutes before transferring to a wire rack to cool completely.
NOTE: CHILLING TIME IS OPTIONAL BUT WILL RESULT IN A THICKER COOKIE.
NOTE: REMOVE THESE COOKIES FROM THE OVEN AS SOON AS THE EDGES APPEAR GOLDEN BROWN.
NOTE: BE SURE YOUR BAKING SODA IS FRESH! IF IT IS NOT, YOUR COOKIES WILL TURN OUT FLAT.