There's no need to make a special sauce for these pears; just mix a little vanilla ice cream with the pear juices.
Peel 4 firm, ripe Bosc pears, and core from the bottom using a melon baler, leaving stems intact. In a 2-qart microwave-safe dish with a lid, place 2 tablespoons light-brown sugar and 1 tablespoon unsalted butter, and add pears. Cover, and microwave on high until the pears are tender enough to pierce with a knife, 10 to 12 minutes (timing will vary depending upon ripeness of pears). Don't be concerned if pears fall over on their sides as they cook. Carefully uncover, as dish lid will release steam.
Transfer cooked pears to four shallow serving bowls, leaving juices behind. Add 1/4 cup vanilla ice cream to the juices of the dish; stir until smooth and saucy. Dividing evenly, spoon sauce around the pears; serve at room temperature or chilled.
Whip the cream: In a large bowl, whisk remaining 2/3 cup cream and granulated sugar until soft peaks form.
Assemble: In each of eight shallow dishes, arrange 2 banana halves lengthwise. Place 2 scoops ice cream on bananas. Top with butterscotch sauce, whipped cream, and, if desired, peanuts and a cherry.
You can serve these warm, or you can make the pears and the sauce, store them separately in the refrigerator, and serve chilled.