Line two cookie sheets with parchment paper and set aside. Preheat your oven to 350 degrees.

In a medium sized bowl, combine all of your dry ingredients (flour, baking powder, baking soda, salt) and set aside. In another medium sized bowl, combine butter and sugar. Add egg and beat well. Next, add your banana, milk, vanilla extract and lemon juice. Mix until well combined and there are very little banana lumps left.

Stir in dry ingredients until well incorporated.

Add the Nutella one tablespoon at a time. You should have four dollops of Nutella on your batter. using a kitchen spatula, fold the batter 3 times. Anything more than three times will begin to mix the nutella into the batter and get rid of the swirls.

Scoop the batter using an ice cream scoop onto the parchment paper lined cookie sheets. Leave 1 ½ - 2 inches between each scoop. Bake for 12-15 minutes until you are able to stab them with a toothpick and it comes out clean.

Once removed from the oven, let them cool completed before you start assembling your whoopie pies. This recipe will make about 8 whoopie pies. On the bottom side of one of the cookie, slather on as much Nutella as your little heart desires. Add some chopped/candied nuts over the top of the Nutella for some added crunch. Place another cookie on top and place back onto the parchment. Continue the process until you've assembled all the whoopie pies.

If you'd like to harden them up a bit, you can place them in the fridge for a couple of minutes or eat them as is. Store them in an air-tight container for up to three days.