Preheat oven to 375 degrees F. In a stand mixer or in a large bowl with a hand mixer, cream together peanut butter with mashed banana and both kinds of sugar until it’s a smooth mixture. Then mix in eggs, one at a time.
In a separate bowl, whisk together flour, salt, and baking soda. Slowly mix that into the creamed butter. Stir in rolled oats.
Making heaping tablespoon-sized cookies out of the dough and spread them out on baking sheets lined with parchment paper.
Bake cookies at 375 degrees F. for 10-12 minutes, rotating the sheet pans once halfway through. The cookies are done when they are a light golden brown around the edges. It’s okay if they are soft in the center.
Remove cookies and let cool. Optionally, use a fork to press crosshatches into the cookies in the traditional peanut butter cookie fashion. Finish cooling on a wire rack. Store cookies in the fridge if storing longer than a day.