Gather all ingredients. Preheat the oven to 400 degrees F (200 degrees C).
Microwave mirepoix in a small bowl, uncovered, on High until thawed, 1 to 2 minutes.
Add pastina, chicken broth, stock base, and thawed mirepoix to an 8-x 8-inch baking dish and stir carefully to combine. Cover with aluminum foil and very gently place in the oven.
Bake in the preheated oven until pastina is al dente (tender with a bite) and liquid is almost absorbed, 35 to 40 minutes. Remove foil carefully and stir in Parmesan cheese. Let sit for 5 minutes before serving.
Serve with additional Parmesan cheese and black pepper. Recipe developed by Isabelle Easter