Fig is a little unexpected but definitely welcome in this layered ice cream cake. The cookies are soft enough to cut through even when frozen. Chocolate and vanilla are classic, but feel free to mix it up-lemon sorbet and strawberry ice cream would be great, too!
Let the chocolate ice cream soften slightly at room temperature for about 10 minutes. Evenly spread it on the bottom of an 8-inch springform pan. Freeze until hardened, about 30 minutes. Arrange 18 of the fig cookies in an even layer over the ice cream (don't press them into it) so they fit snugly together, cutting to fit if necessary.
Meanwhile, let the vanilla ice cream sit at room temperature for about 10 minutes. Evenly spread it over the cookies. Cover the top of the cake with plastic wrap, and freeze until solid, at least 4 hours up to overnight.
When ready to serve, remove the plastic wrap and let the cake sit at room temperature for 10 minutes. Meanwhile, cut the 2 remaining fig cookies into thin slices. Whip the cream with an electric mixer on medium speed in a small bowl until firm peaks form; stir in the sugar.
Run a knife around the cake edge, and remove the springform collar. Top the cake with the whipped cream, and sprinkle with the cookie slices. Cut into slices with a sharp, heavy knife.