Preheat the oven to 180°C/gas 4. Lightly butter a large ovenproof large dish with a depth of about 5cm. Pour the milk into a saucepan and add the lemon zest. Bring to a simmer, remove from the heat and set aside.
Soak the cranberries in the amaretto.
Spread the butter over the slices of Pandoro and cut into triangles.
Place the buttered Pandoro into the dish, over lapping the slices.
Beat the eggs and sugar together and stir in the milk.
Scatter three quarters of the almonds and all soaked cranberries over the Pandoro.
Pour the custard mixture over the sliced Pandoro and leave to soak for about 5 minutes. Using your fingers, gently push the Pandoro down into the mixture.
Scatter with the remaining flaked almonds then place the dish in a roasting tin containing enough hot water to come halfway up the sides of the dish. Bake for about 50-55 minutes, until the custard is lightly set and the top is golden brown. Serve with cream.