Line a rimmed cookie sheet with waxed paper. Peel the bananas and cut in half crosswise. Insert a skewer into the flat end of each banana half and place on the cookie sheet; freeze for 3 to 4 hours, or until solid. Melt the chocolate with the shortening in the microwave or on the stovetop over very low heat. Dip the frozen bananas one at a time into the melted chocolate mixture, using a spoon if necessary to ladle the chocolate over the bananas, allowing excess chocolate to drip back into the pan. Immediately roll the coated bananas in the chopped peanuts. Return the bananas to the cookie sheet, cover, and freeze for at least 2 hours before serving. After that, store in resealable plastic storage bags and keep frozen until ready to use.
