Parboil egg plant until tender, but not soft in boiling, salted water. Cut in half crosswise with a sharp knife. Scrape out the inside and do not break the skin.
Heat 1 tablespoon butter or fat, add the onion, brown, then scraped egg plant, bread crumbs, salt and pepper to taste and the egg yolk. Mix well together, refill shells, place in dripping pan, in oven-baste with butter or sprinkle cracker crumbs on top with bits of butter-baste often and brown nicely.