Chocolate-Dipped Frozen Banana Bites

2   cups bittersweet chocolate chips
2   tablespoons oil
Assorted toppings for coating banana (such as toffee bits, chopped salted pecans, or toasted shredded sweetened coconut)
3   ripe bananas, peeled, cut into ½-inch-thick slices

Stir chocolate and oil in heavy small saucepan over low heat just until smooth.  Let stand 15 minutes to cool.
Place each topping separate shallow dish.  Line baking sheet of foil.  Arrange banana slices on foil.  Using fingers, dip 1 banana slice in chocolate coating completely, shake off excess chocolate.  Drop dipped banana in 1 topping using clean hand,  sprinkle more topping over banana to coat, transfer to foil-lined sheet.  Repeat with remaining bananas, chocolate and toppings.  Freeze until firm, about 3 hours, then serve.