In a medium bowl, mix the butter and sugars together until creamy. Add the eggs and vanilla and mix together.

Add the peanut butter and mix until it well combined.

In a separate mixing bowl, combine the whole-wheat flour and baking soda until well mixed. Add to the bowl of batter and mix well.

Add the oats, if using, and stir until well combined.

Refrigerate or freeze the dough for at least 3 hours or overnight as desired.

Preheat the oven to 350 degrees.

Put parchment paper down on 1 to 2 baking sheets.

Using a spoon, make roundish balls of dough, about the size of a half-dollar, and put them on the baking sheet, spaced about an inch and a half apart. Bake for 8 to 9 minutes. Cookies should be lightly brown on the top and, once cooled, should be slightly soft.

Remove from the oven and allow to cool slightly, then move to a rack or implement for cooling.