In a heavy, medium saucepan, combine the milk, rice, sugar, vanilla seeds, vanilla pod, and salt. Bring to a boil over medium heat, stirring frequently. Reduce the heat to medium-low and simmer, stirring occasionally, until the rice is tender, about 35 minutes. In a medium bowl, mix together the lemon juice, amaretto, and lemon zest. Slowly stir the lemon mixture into the rice mixture and cook for 10 minutes longer. Remove the vanilla pod and discard. Stir in the whipping cream (mixture will still be runny but will thicken as it cools). Spoon the rice pudding into bowls. Cover and refrigerate for at least 4 hours.
Sprinkle the chilled rice pudding with sliced almonds and serve.
To toast the almonds, arrange them in a single layer on a baking sheet. Bake in a preheated 350 degrees F oven until lightly toasted, about 6 to 8 minutes. Cool completely before using.