1. Roast the chilies over the flame of the stove; peel their skins. Slice the chilies and remove the seeds. Blanch in boiling water and dry on paper towel. Fill one half of a chili with cheese and cover with the other half.
2. Dip each stuffed chili in the beaten eggs and dredge in flour to cover. Fry in hot oil.
3. In a saucepan heat the butter with the tomato sauce; add the fried chilies and cook over low heat for 10 more minutes. Serve hot.