Cut butter in half. In a microwave safe bowl, heat in microwave 10 15 seconds to soften. Be careful not to melt butter.
In a large bowl, use a mixing spoon to blend butter, banana, and sugar.
Add peanut butter and brown sugar. Continue mixing until completely combined.
Add egg and vanilla. Mix until smooth.
Add flours and baking soda. Mix until smooth.
Stir in rolled oats. If using chocolate chips or raisins, gently stir in now.
Scoop dough with a teaspoon. Shape into 1 inch balls. Place dough balls 2 inches apart on an ungreased baking sheet. Flatten dough balls by using a fork to make a criss cross pattern on the cookies.
Bake on middle rack of oven until cookies are lightly browned on bottom, about 8-10 minutes. Remove from oven. Let sit 5 minutes to firm up. Remove from tray.
Chef’s notes:
Cookies may take a little more or less time to brown depending on your oven.
For a quick snack, crumble cookies on top of ½ cup low fat plain yogurt.