Pulse 1/2 cup of the granola in the bowl of a food processor. Combine the granola crumbs, melted butter and remaining granola in a bowl and stir until damp.
Place paper liners in 18 muffin cups. Spoon the crust mixture into each cup and press until firm. Bake for 5-8 minutes. Set aside to cool.
Meanwhile, mix the sour cream, sugar and puréed berries. In a cold bowl, beat the whipping cream until firm (approximately 4 minutes) and then fold in the sour cream mixture. Spoon the filling into the cooled muffin cups (almost to the top). Freeze for at least 2 hours.
To serve, remove the muffin cup liners and place on plates. If desired top with additional whipped cream and garnish with fresh berries and mint.