Chocolate Chip and Banana Ice Cream Sandwiches

Preheat oven to 350 °F. If using dough log, cut into 20 equal-size rounds. Arrange sliced dough rounds (or 20 pre-portioned rounds) on 2 baking sheets, spacing evenly. Using fingertips, press each into 2 1/2-inch round. Bake cookies until golden, about 11 minutes for sliced rounds and 15 minutes for pre-portioned dough. Transfer to rack; cool. Line baking sheet with foil; place in freezer. Place 1 cookie, flat side up, on work surface. Top with 1/3 cup ice cream; spread almost to edge. Top with single layer of bananas. Sandwich with another cookie; press gently to compact. Place on baking sheet in freezer. Repeat with remaining cookies, ice cream, and bananas. Freeze 2 hours. Using knife, smooth sides of ice cream sandwiches. Freeze 1 hour. Place chocolate chips and oil in small glass bowl; microwave on medium-high until chocolate is melted, stopping occasionally to stir, about 1 1/2 minutes. Let stand just until cool, about 10 minutes. Place granola or toffee (if using) on plate. Dip 1 ice cream sandwich halfway into melted chocolate; lift and quickly shake excess chocolate back into bowl. If desired, roll dipped edge in granola or toffee; return to baking sheet in freezer. Repeat with remaining sandwiches, chocolate, and granola or toffee. Freeze until firm, about 2 hours. DO AHEAD: Can be made 2 days ahead. Wrap each sandwich in foil; keep frozen.