Preheat oven to 375 degrees F (190 degrees C). Line an 8x8-inch baking dish with aluminum foil, letting foil hang down over the sides of the pan; spray pan with cooking spray.
Stir oats, wheat germ, flax seed, protein powder, cinnamon, and salt together in a bowl. Mash bananas in a separate large bowl and stir 1/4 cup Jif(R) peanut butter, honey, and vanilla extract into bananas, mixing well. Stir dry ingredients into banana mixture and spread into the prepared baking dish.
Bake in the preheated oven for 20 minutes. Spread 1/4 cup natural peanut butter over top.
Continue baking until lightly browned on the edges and set, 10 more minutes. Let cool in the pan and lift bars onto a work surface using aluminum foil as handles. Cut into bars, wrap in plastic wrap, and store in refrigerator.
