In a small saucepan or pot, add the broth and bring it up to a soft boil.
Add the pastina to the broth and simmer until cooked through and the broth is almost completely absorbed, about 7 minutes. You may need to add more broth depending on how much has been absorbed.
Once the pastina is cooked through, turn off the heat and add one whole egg to the pan. Gently and quickly fold the egg in so it combines with the pastina and doesn't scramble into large pieces.
Add butter and cheese and allow them to melt. Top with more cheese, salt, and black pepper, if desired.
Notes
Source recipe gives cook time and total time as 10 minutes with no separate prep time listed. May need additional broth depending on pasta brand; keep an extra cup on hand. Best eaten fresh due to the softly cooked egg; refrigerate leftovers up to 2-3 days if needed. Not recommended for freezing.
Keyword comfort pasta, dinner recipe, pastina with egg, quick pasta recipe