Put 16 mini-muffin liners in a mini-muffin tin. Arrange 16 banana slices in the muffin tin. Set aside.
Stir together peanut butter, Greek yogurt, vanilla extract, and salt in a bowl. Put about 1 teaspoon of mixture on each of the banana slices in the muffin tins. Top with another slice of banana.
Put chocolate chips and coconut oil in a microwave safe bowl. Microwave for 25 seconds. Stir and repeat in 25 second intervals until smooth.
Drizzle about 1 to 2 teaspoon chocolate onto each banana bite, letting it drip off the sides. Put in the freezer for about 30 minutes before serving. Keep covered in a tightly covered container in the freezer for up to 1 month.