Preheat oven to 180ºC/350ºF.
Add the bananas to a bowl, mash until smooth, then add the lemon zest, apple cider vinegar, melted butter and milk, stir well until smooth, then mix in the peanut butter.
Fold in the cinnamon, baking soda and flour until it turns into a smooth batter, then pour into a loaf tin lined with parchment paper. Use a spoon to spread the batter evenly. Top the batter with the teaspoons of peanut butter and swirl with a toothpick.
Bake for 40 minutes or until a skewer comes out clean.
Slice into soldiers for babies, along with a few raspberries.