In a large bowl, using a wooden spoon, quickly stir together ice cream, mashed bananas, walnuts and toffee bits until smooth. Spread evenly into baked pie crust and freeze immediately until solid, at least 4 hours and up to 2 days.
In a bowl, whip cream until it is light and fluffy. Cut banana into 12 slices. Spread whipped cream evenly over frozen pie. Top with walnut halves and banana slices.
Chef's Tip: To soften ice cream, place container in the refrigerator for 30 minutes.