This isn't really a recipe, but the basic technique I like is 4-to-1 liquid-to-pastina by weight, or 3-to-1 by volume, but volume measurements will depend on the specific shape of pastina you're using. Bring the liquid to a boil, stir in the pastina, cook until almost done, take it off the heat, season, melt in some butter and cheese, and when the bubbling has fully stopped, stir in an egg or egg yolk.