In a medium saucepan, bring the chicken or vegetable broth to a gentle boil over medium-high heat.
Once boiling, stir in the pastina. Reduce the heat to medium-low, cover partially, and simmer, stirring occasionally, for about 8-10 minutes, or until the pasta is al dente and has absorbed most of the liquid. Keep an eye on it to prevent sticking.
Remove the saucepan from the heat. Stir in the butter until it melts completely.
Gradually whisk in the heavy cream and grated Parmesan cheese until the soup is smooth and creamy. Continue stirring until the cheese is fully incorporated and the soup has thickened slightly.
Season generously with salt and freshly ground black pepper to your taste. Remember that Parmesan cheese is salty, so taste before adding too much salt.
Ladle the creamy pastina into bowls. Garnish with extra Parmesan cheese and fresh chopped parsley, if desired. Serve immediately.