In a medium-size bowl mix together crushed cones, walnuts and butter until combined. Press into the bottom of a 9-inch springform pan. Freeze for 10 minutes.
Soften half of the frozen yogurt. Stir in mashed bananas and banana extract. Spread over crust; freeze for 30 minutes. Spread warmed fudge sauce on top (see Note). Sprinkle walnuts over fudge sauce. Freeze for 30 minutes.
Soften remaining frozen yogurt. Swirl in 1 cup of the strawberry sauce. Spread on top. Cover; freeze overnight.
Remove from the freezer 10 minutes before serving. Remove the side of the springform pan and peel off waxed paper. Slice into 16 servings. Serve with remaining strawberry sauce and whipped topping.