Place the chocolate chips into a glass bowl and put into the microwave. Cook for 30 seconds then stir; cook for an additional 15 seconds then stir; cook for an additional 10 or so seconds until melted. Don't overcook! Once the chocolate is melted add the peanut butter and stir until well combined. Pour the mixture into the milk along with the vanilla. Blend using an immersion blender for 30 seconds or until well combined. Add the frozen sliced bananas and blend with an immersion blender until creamy and smooth. Serve immediately. Enjoy.