Slice bananas into ¼-inch slices. Spread Nutella on one banana and top with another. Secure the two banana slices together with a toothpick to secure together. Put the banana "sandwiches" in the freezer for about 30 minutes.
Melt chocolate in a microwave safe bowl or in a double boiler on the stovetop. Place sprinkles in a bowl.
Dunk banana sandwiches in the chocolate to completely coat. Then dip in the sprinkles. Remove the toothpick quickly as the chocolate will start to harden right away.
Place on parchment paper and let sit for 15 minutes to chocolate can completely harden. Store bananas in fridge if not eating right away.