Cook pasta shells according to package directions. In large skillet saute onion and garlic in butter. Add and saute ground beef. Remove from heat, stir in bread crumbs, set aside to cool. Blend in egg, Parmesan cheese and nutmeg and salt and pepper to taste.
Pour 1/2 can spaghetti sauce into greased 2 quart baking dish. Using a small spoon, carefully fill each shell with meat filling. Place stuffed shells, side by side, filling side up into baking dish. Spoon remaining sauce over shells, sprinkle generously with Parmesan cheese. Cover and bake at 375 degrees for 35- 40 minutes.
