Sauté the sardines (reserve the broth) with olive oil, onion, cilantro, peppers, tomato (the tomato if consumed within 24 hours) and half of the chicken broth.
Beat everything in a blender, eggs, milk, wheat flour, oil, sardine broth, grated cheese, and half of the chicken broth, until the dough is light.
Grease the baking dish with oil and wheat flour, pour the dough and the stuffing on top. If desired, sprinkle a little grated cheese on top.