Line 8x4-inch loaf pan with foil. In large bowl, beat cream, sugar and vanilla with electric mixer on high speed until stiff peaks form.
Spread 3/4 cup of the whipped cream evenly in bottom of pan. Place 3 granola thins, chocolate side up, on top of cream. Top with 3/4 cup whipped cream. Sprinkle 1/2 cup of the cereal evenly over top. Spread 3/4 cup of the whipped cream over cereal.
Repeat layering with 3 granola thins and 3/4 cup whipped cream. Top with remaining 1/2 cup cereal, 3/4 cup whipped cream and 3 granola thins. Cover loosely with plastic wrap. Freeze until firm, at least 4 hours or up to 2 days.
To serve, let cake stand at room temperature 5 minutes. Remove plastic wrap. Place serving platter upside down over pan; turn platter and pan over. Remove pan and foil. Break remaining granola thin into pieces; sprinkle over top. With sharp knife, cut crosswise into 1-inch-thick slices.