Grease a 28 cm springform cake tin and line the base with baking paper. Grease the paper very well. Mix the butter and Amaretti biscuits and press into the tin.
Pour the filling over the base and bake for 35 minutes, or until set. Allow to cool.
To make the topping, mix the raspberries with the liqueur, reserving a few raspberries to garnish. Mix the sour cream and sugar by hand and spoon over the raspberries. Spread onto the topping and bake at 100°C for 10 minutes. Allow to cool, then cover and chill for 24 hours.
To serve, sprinkle with the toasted almonds and garnish with the reserved raspberries, mint and flowers.